LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

%  Class 


WORKS   OF   H.  M.  WILSON 

PUBLISHED    BY 

JOHN  WILEY  &  SONS. 


Topographic  Surveying. 

Including-  geographic,  exploratory,  and  military 
mapping,  with  hints  on  camping,  emergency  surgery, 
and  photography.  Third  Edition,  Revised.  Illus- 
trated by  18  engraved  colored  plates  and  205  half-tone 
plates  and  cuts,  including  two  double-page  plates. 
8vo,  xxx  -f  yio  pages.  Cloth,  $3.50. 

Irrigation  Engineering. 

PART  I.  HYDROGRAPHY.  PART  II.  CANALS  AND 
CANAL  WORKS.  PART  III.  STORAGE  RESERVOIRS. 
Sixth  Edition,  Revised  and  Enlarged.  8vo,  xxix  + 
625  pages;  38  full-page  plates  and  195  figures,  in- 
cluding many  half-tones.  $4.00. 


IRRIGATION  ENGINEERING 


BY 

HERBERT  M.  WILSON,  C.E. 

Member  American  Society  of  Civil  Engineers ;  C kief  Engineer  and  former  Geografher 

and  Irrigation  Engineer •,  United  States  Geological  Survey ; 

Author  of"  Topographic  Surveying"  etc. 


SIXTH  EDITION,  REVISED  AND  ENLARGED 
TOTAL  ISSUE  SEVEN  THOUSAND 


NEW   YORK: 

JOHN  WILEY  &  SONS 

LONDON:  CHAPMAN  &  HALL,  LIMITED 

1909 


Copyright,  1896,  1903,  1905,  1909 

BY 

HERBERT  M.   WILSON 


COMPOSITION    AN7D    ELECTROTYPING    BY    PUBLISHERS    PRINTING   CO.,    NEW   YORK,    U.S.A. 


PREFACE  TO  FIRST  EDITION 

THE  need  of  a  comprehensive  treatise  on  irrigation  has  been  so 
frequently  brought  to  my  attention  during  the  last  few  years,  that 
I  have  undertaken  to  write  this  book  with  the  hope  that  it  may  help 
those  who  are  engaged  in  the  study  or  practice  of  irrigation  engineer- 
ing. It  is  chiefly  the  result  of  original  investigation,  the  descrip- 
tions of  works  being  made  from  personal  observation  in  America, 
Europe,  and  India. 

Some  of  the  matter  contained  in  Part  I  is  compiled,  and  in  its 
preparation  I  am  especially  indebted  for  information  and  sugges- 
tions to  the  valuable  work  on  "Water  Supply  Engineering,"  by 
Mr.  J.  T.  Fanning.  There  is  added,  however,  much  that  is  new, 
a  portion  of  which  was  obtained  from  the  reports  of  Mr.  F.  H. 
Newell,  Chief  Hydrographer  of  the  U.  S.  Geological  Survey.  The 
purpose  has  been  to  include  in  Part  I  only  so  much  of  hydraulics 
as  is  an  indispensable  preliminary  to  the  remainder  of  the  book,  or 
is  original  matter.  Wherever  the  subject  has  been  treated  by  others 
the  reader  is  referred  to  their  works. 

The  entire  book  relates  directly  to  the  conditions  surrounding 
Western  irrigation  practice.  The  examples  given  and  the  sugges- 
tions made  apply  immediately  to  Western  methods,  though  many 
useful  hints  are  borrowed  from  foreign  experience.  The  classifica- 
tion adopted  is  original,  I  believe,  and  follows  closely  that  employed 
in  reports  made  by  me  to  the  Government,  which  seem  to  have 
met  with  general  approval.  In  this  classification  the  terms  "diver- 
sion weirs"  and  "dams"  have  been  used  with  special  signification. 

iii 


190880 


iv  PREFACE   TO   FIRST   EDITION 

Under  the  term  "diversion  weirs"  are  included  all  obstructions 
built  across  running  streams  and  designed  to  act  as  overflow  weirs, 
though  their  functions  may  be  those  either  of  storage  dams  or 
diversion  weirs  or  both.  Under  the  term  "dams"  are  included  all 
retaining  walls,  of  whatsoever  material,  which  are  intended  only 
to  impound  water  and  are  not  so  constructed  as  to  withstand  the 
shock  of  falling  water.  These  classes  necessarily  overlap  to  some 
extent. 

The  subject  of  the  application  of  water  to  crops  is  but  briefly 
touched  upon.  It  would  in  itself  require  a  volume,  and  is  one 
of  more  interest  to  the  farmer  than  to  the  engineer.  Part  III, 
which  treats  of  storage  works,  contains  much  new  material  never 
before  brought  together,  and  this  is  especially  true  of  the  chapters 
on  Earth  Dams  and  Pumping.  The  theory  of  high  masonry 
dams  is  but  briefly  considered,  as  this  subject  has  already  been 
exhaustively  treated  by  previous  writers,  to  whose  works  reference 
is  made.  What  little  has  been  said  concerning  it  is  partly  com- 
piled, the  chief  source  being  Wegmann's  admirable  treatise  on 
masonry  dams.  Great  care  has  been  taken  throughout  the 
volume  to  avoid  the  use  of  mathematics,  since  many  of  the  for- 
mulas given  on  the  flow  of  water  in  open  or  closed  channels,  on 
the  discharge  from  catchment  basins,  and  on  strains  in  masonry 
dams  are  exceedingly  faulty  and  misleading.  We  have  much 
to  learn  before  we  can  apply  mathematics  to  these  subjects  with 
accuracy.  I  consider  it  better  to  follow  practical  usage  and 
experience  than  theory  where  the  latter  is  founded  on  doubtful 
premises  and  is  liable  to  produce  inaccurate  results  if  adhered 
to  closely. 

The  endeavor  has  been  to  prepare  a  work  which  will  be  of 
value  to  the  practical  engineer  as  well  as  to  the  student.  It  was 


PREFACE    TO    FIRST   EDITION  V 

found  impossible  to  include  within  the  covers  of  one  volume  the 
necessary  tables  on  hydraulics  and  flow  of  water.  It  is  believed, 
however,  that  this  book  contains  much  that  will  be  useful  to  the 
practical  engineer,  and  that  the  teacher  of  irrigation  engineering 
will  find  the  facts  assembled  in  such  manner  as  to  be  materially 
helpful. 

The  effort  has  been  to  illustrate  all  the  important  works  de- 
scribed, as  well  as  types  of  works,  in  order  that  practising  engineers 
may  obtain  suggestions  from  the  experience  of  others. 

I  am  indebted  to  the  courtesy  of  the  Director  of  the  U.  S. 
Geological  Survey  for  numerous  electrotypes  of  illustrations,  which 
had  been  previously  published  in  reports  made  by  me.  Several 
illustrations  were  also  obtained  through  the  courtesy  of  the  Secretary 
of  the  American  Society  of  Civil  Engineers,  being  electrotypes  of 
those  used  in  papers  read  by  me  before  that  society. 

WASHINGTON,  D.  C.,  January,  1893. 


PREFACE  TO  FOURTH  EDITION 

CONGRESS  has  recently  enacted  a  reclamation  law  whereby 
for  the  first  time  in  the  history  of  our  country  provision  has  been 
made  for  the  systematic  construction,  on  a  large  scale,  of  public 
works  other  than  those  for  river  and  harbor  improvement.  Pro- 
vision was  made  by  which  about  $2,500,000  will  annually  accrue 
in  the  Treasury  to  the  credit  of  the  Secretary  of  the  Interior  for  the 
construction  of  works  for  the  irrigation  of  the  lands  of  the  arid 
region  under  the  supervision  of  the  Director  of  the  United  States 
Geological  Survey.  Already  a  number  of  important  projects  have 
advanced  to  a  point  where  construction  may  be  begun.  The 
magnitude  of  the  work  proposed  is  evident  when  it  is  realized  that 
ten  years  hence  $30,000,000  may  have  been  expended  upon  this 
work  without  further  act  of  legislation.  Within  a  year  nearly  200 
engineers,  young  and  old,  have  found  employment  upon  this  work. 
The  importance  to  the  profession,  therefore,  of  a  knowledge  of  the 
underlying  principles  of  irrigation  engineering  has  suggested  the 
necessity  for  an  exhaustive  revision  of  this  book. 

Since  the  issue  of  the  second  edition  there  have  been  few  import- 
ant developments  in  hydraulic  engineering,  consequently  the  present 
revision  does  not  affect  any  portion  of  the  book  radically,  though  it 
has  been  sufficiently  thorough  to  affect  every  portion  more  or  less. 

There  have  been  constructed  recently  a  number  of  great 
storage-dams  both  of  masonry  and  of  loose  rock,  and  important 
changes  in  existing  structures  have  been  made.  These  are  noted 
in  Part  III,  in  which  the  greatest  amount  of  textual  change  has 


Mil  PREFACE    TO    FOURTH    EDITION 

been  made.  Especially  interesting  in  this  connection  is  the  great 
overfall  weir  at  Assuan,  Egypt;  the  rock-fill  dams  of  California, 
and  the  development  in  arched  and  combined  masonry  and  metal 
dams  in  the  West.  The  chapter  on  sub-surface  water  sources 
has  been  materially  improved  as  a  result  of  the  work  of  Prof. 
Slichter,  of  Wisconsin.  The  chapter  on  rainfall  and  run-off  of 
streams  has  been  brought  up  to  date  and  extended,  thus  adding 
to  its  usefulness. 

I  ahi  especially  indebted  for  information  to  the  admirable 
series  of  water-supply  papers  of  the  U.  S.  Geological  Survey, 
numbering  now  eighty,  nearly  all  of  which  have  been  published 
since  the  last  revision.  Many  useful  data  have  also  been  obtained 
from  Mr.  J.  D.  Schuyler's  report  on  reservoirs  for  irrigation, 
published  in  the  Eighteenth  Annual  Report  of  the  same  bureau; 
also  from  Messrs.  Turneaure  and  Russell's  "  Public  Water  Sup- 
plies," and  the  various  technical  papers  which  have  appeared 
from  time  to  time  in  Engineering  News. 

H.  M.  W. 

•     WASHINGTON,  D.  C.,  November,  1903. 


PREFACE  TO  SIXTH   EDITION 

THE  Reclamation  Service  of  the  United  States  now  has  21 
projects  which  have  reached  such  a  state  of  completion  that  water 
is  being  furnished  settlers  for  irrigation  of  their  lands.  At  this 
date  675,514  acres  are  under  irrigation  from  Reclamation  projects 
and  $42,932,787  have  been  expended  upon  the  construction  of 
works  completed  or  in  progress.  The  revenues  collected  to  date 
from  projects  in  operation  and  available  under  the  law  for  re- 
expenditure  on  future  construction  amoupt  to  $1,070,596. 

The  present  edition  has  been  almost  entirely  rewritten,  bringing 
up  to  date  the  tremendous  progress  made  in  construction  by  the 
Reclamation  Service.  Since  the  last  edition  important  changes 
have  been  produced  in  the  design  and  in  the  materials  used  in 
structures  on  irrigation  works  as  a  result  of  the  very  general  adop- 
tion of  reinforced  concrete  for  such  works.  Every  chapter  and 
every  article  of  this  edition  has  undergone  changes,  including  the 
elimination  of  much  old  matter  and  forty  illustrations  and  the 
introduction  of  a  large  amount  of  new  textual  matter  and  eighty 
new  illustrations,  representative  of  more  modern  designs  for 
irrigation  works.  I  am  indebted  for  information  contained  in  this 
revision  chiefly  to  the  annual  reports  and  published  specifications 

of  the  Reclamation  Service. 

H.  M.  W. 

WASHINGTON,  D.  C.,  April  i,  1909. 


ix 


CONTENTS 


CHAPTER  I 

INTRODUCTION 
ART.  PAGE 

1.  Meaning  of  Irrigation i 

2.  Extent  of  Irrigation 2 

3.  Control  of  Irrigation  Works 2 

4.  Value  as  an   Investment 3 

5.  Incidental  Values 4 

6.  Cost  and  Returns  of  Irrigation 4 


PART    I 
HYDROGRAPHY 

CHAPTER  II 

PRECIPITATION,    RUNOFF,    AND   STREAM   FLOW 

7.  Relation  of  Rainfall  to  Irrigation 7 

8.  General  Rainfall  Statistics 7 

9.  Rainfall  Distribution  in  Detail 8 

10.  Great  Rainfalls 9 

11.  Suddenness  of  Great  Storms 1 1 

12.  Precipitation  on  River  Basins 1 1 

13.  Rainfall  Statistics  by  States 1 1 

14.  Gauging  Rainfall 1 1 

15.  Runoff 14 

16.  Variability  of  Runoff 14 

17.  Relation  of  Rainfall  to  Runoff 15 

18.  Formulas  for  Maximum  Runoff 16 

19.  Flood  Discharges  of  Streams 17 

20.  Amounts  of  Stream  Discharge  and  Runoff 17 

21.  Discharge  in  Seasons  of  Minimum  Rainfall 20 


xii  CONTENTS 

ART.  PAGE 

22.  Regimen  of  Western  Rivers 20 

23.  Mean  Discharge   of  Streams 21 

24.  Available  Annual  Flow  of  Streams 21 

25.  Works  of  Reference:    Precipitation,  Runoff,  and  Stream   Flow 21 


CHAPTER  III 

EVAPORATION,    ABSORPTION,    AND   SEEPAGE 

26.  Evaporation  Phenomena 23 

27.  Measurement  of  Evaporation 23 

28.  Amount  of  Evaporation  .  .  . 25 

29.  Evaporation  from  Snow  and  Ice 25 

30.  Evaporation  from  Earth ' 27 

31.  Effect  of  Evaporation  on  Water  Storage 28 

32.  Percolation  and  its  Amount 28 

33.  Absorption  29 

34.  Amount  of  Absorption  in  Reservoirs  and  Canals 30 

35 .  Prevention  of  Perlocation 30 

36.  Seepage  Water 31 

37.  Amount  of  Seepage  Water 31 

38.  Works  of  Reference:    Evaporation,  Absorption,  and  Seepage 33 


CHAPTER  IV 

ALKALI,    DRAINAGE,    AND   SEDIMENTATION 

39.  Harmful  Effects  of  Irrigation 34 

40.  Alkali 34 

41.  Causes  of  Alkali 34 

42.  Waterlogging 35 

43.  Prevention  of  Alkali  and  Waterlogging 35 

44.  Chemical  Treatment 36 

45.  Mulching  and  Leaching 38 

46.  Growth  of  Suitable  Plants 38 

47.  Drainage 39 

48.  Excessive  Use  of  Water 39 

49-  Silt 40 

50.  Character  of  Silt 40 

51.  Amount  of  Silt. 41 

52.  Prevention  of  Sedimentation  in  Reservoirs  and  Canals 42 

53.  Fertilizing  Effects  of  Sediment 44 

54.  Weeds 44 

55.  Malarial  Effects  of  Irrigation 44 

56.  Works  of  Reference:    Alkali,  Drainage,  and  Sedimentation 46 


CONTENTS  xiii 


CHAPTER  V 


QUANTITY   OF    WATER    REQUIRED 
ART.  PAGE 

57.  Duty  of  Water 47 

58.  Units  of  Measure  for  Water  Duty  and  Flow .  47 

59.  Measurement  of  Water  Duty   50 

60.  Duty  per  Second-foot 51 

61.  Duty  for  Various  Crops 52 

62.  Depth  of  Water  Required  tc  Soak  Soil    52 

63.  Quantity  per  Service  and  Irrigating  Period 53 

64.  Duty  per  Acre-foot 53 

65.  Linear  and  Areal  Duty 54 

66.  Percentage  of  Waste  Land 5^ 

67.  Tatils,  or  Rotation  in  Water  Distribution 55 

68.  Works  of  Reference:    Duty  of  Water 57 


CHAPTER  VI 

FLOW    AND    MEASUREMENT   OF    WATER    IN   OPEN    CHANNELS. 

69.  Physical  and  Chemical  Properties  of  Water    58 

70.  Weight  of  Water 58 

7 1 .  Pressure  of  Water 58 

72.  Amount  of  Pressure  of  Water    59 

73.  Center  of  Pressure    59 

74.  Atmospheric  Pressure 60 

75.  Motion  of  Water 60 

76.  Factors  Affecting  Flow 61 

77.  Formulas  of  Flow  in  Open  Channels 61 

78.  Kuttcr's  Formula    62 

79.  Tables  for  Use  with  Kutler's  Formula 64 

80.  Discharge  of  Streams  and  Velocities  of  Flow    65 

81.  Surface  and  Mean  Velocities    70 

82.  Measuring  or  Gauging  Stream  Velocities 70 

83.  Current  Meters   72 

84.  Gauging  Stations 74 

85.  Use  of  the  Current  Meter 7^ 

86.  Rating  the  Meter   76 

87.  Rating  the  Station    76 

88.  Measuring  Weirs 77 

89.  Rectangular  Measuring  Weir    77 

90.  Francis'  Formulas 78 

91.  Conditions  of  Using  Rectangular  Weir 79 

02.  Trapezoidal  Weirs    79 


xiv  CONTENTS 

ART.  PAGE 

93.  Weir  Gauge  Heights    80 

94.  Tables  of  Weir  Discharge 80 

95.  Broad-crested  Weirs 80 

96.  Measurement  of  Canal  Water    85 

97.  Requisites  of  a  Measuring  Apparatus  or  Module 85 

98.  Methods  of  Measurement 86 

99.  The  Statute  Inch  or  Module 88 

100.  Rating  Flumes    88 

101.  Divisors    89 

102.  Stream  Measurement  Under  Ice 89 

103.  Works  of  Reference:   Flow,  etc.,  of  Water  in  Open  Channels 89 


CHAPTER  VII 

SUBSURFACE   WATER   SOURCES   AND   SEWAGE  FOR   IRRIGATION 

104.  Sources  of  Earth  Waters 91 

105.  Motion  of  Ground  Water 91 

106.  Underflow 93 

107.  Sources  of  Springs  and  Artesian  Wells > 93 

108.  Artesian  Wells 94 

109.  Examples  of  Artesian  Wells 94 

no.  Capacity  and  Cost  of  Artesian  Wells   95 

in.  Storage  of  Artesian  Water 96 

112.  Size  of  Well 96 

113.  Manner  of  Having  Wells  Drilled 97 

1 14.  Varieties  of  Drilling-machines 98 

1 15.  Process  of  Drilling 100 

1 16.  Capacity  of  Common  Wells 102 

117.  Wells,  Power-pumped 103 

1 18.  Tunnelling  for  Water 105 

119.  Underground  Cribwork 106 

1 20.  Other  Subsurface- water  Sources 107 

121.  Sewage  Disposal  107 

122.  Sewage  Irrigation 109 

123.  Fertilizing  Effects  of  Sewage    no 

124.  Effects  of  Sewage  Irrigation  on  Health    in 

125.  Duty  of  Sewage 112 

126.  Methods  of  Laying  out  Sewage  Farms  and  Applying  Sewage 114 

127.  Works  of  Reference:  Subsurface -water  Sources  and  Sewage  for  Irrigation  117 


CONTENTS  XV 

PART   II 

CANALS  AND   CANAL   WORKS 

CHAPTER  VIII 

CLASSES   OF    IRRIGATION   WORKS 
ART.  PAGE 

128.  Gravity  and  Lift  Irrigation 1 18 

129.  Navigation  and  Irrigation  Canals    119 

130.  Sources  of  Supply 119 

131.  Inundation  Canals   120 

132.  Perennial  Canals 123 

133.  Dimensions  and  Cost  of  some  Perennial  Canals 123 

134.  Parts  of  a  Canal  System  125 

CHAPTER  IX 

ALIGNMENT,    SLOPE,    AND   CROSS-SECTION 

135.  Relation  between  Lands  and  Water-supply 126 

136.  Diversion  Works 1 26 

137.  Alignment 127 

138.  Method  of  Survey 1 28 

139.  Linear  or  Trial-line  Survey 1 28 

140.  Contour  Topographic  Survey 130 

141.  Right  of  Way  on  Public  Land;   also  State  Desert-land  Grants 131 

142.  Obstacles  to  Alignment 132 

143.  Sidehill  Canal  Works 133 

144.  Curvature 134 

145.  Borings,  Trial  Pits,  and  Permanent  Marks 134 

146.  Example  of  Canal  Alignment — Ganges  Canal    135 

147.  Example  of  Canal  Alignment — Turlock  Canal 138 

148.  Example  of  Canal  Alignment — Santa  Ana  Canal 143 

149.  Velocity,  Slope,  and  Cross-section 148 

150.  Limiting  Velocity   149 

151.  Grade  for  Given  Velocity 149 

152.  Examples  of  Canal  Velocity  and  Grades 150 

153.  Cross-sections    151 

154.  Form  of  Cross-section   152 

155.  Side  Slopes  and  Top  Width  of  Banks    154 

156.  Cross-section  with  Subgrade 155 

157.  Lined  Canal 155 

158.  Shrinkage  of  Earthwork    159 

159.  Cross-section  in  Rock    .    160 


XVI  .        CONTENTS 


CHAPTER  X 

HEADWORKS   AND   DIVERSION   WEIRS 
ART.  PAGE 

160.  Location  of  Headworks : 162 

161.  Character  of  Headworks  163 

162.  Diversion  Weirs    164 

163.  Classes  of  Weirs 16^ 

164.  Brush  and  Bowlder  Weirs 165 

165.  Rectangular  Pile  Weirs 166 

166.  Open  and  Closed  Weirs 166 

167.  Open  Frame  or  Flashboard  Weirs    168 

168.  Open  Masonry  Weirs,  Indian  Type 1 70 

169.  Laguna  Weir,  Colorado  River 175 

170.  Movable  Iron  Weirs,  French  Type 176 

171.  Rolling  Lift  Weir 177 

172.  Construction  of  Crib  Weirs 179 

1 73.  Wooden  Crib  and  Rock  Weirs ^ 1 79 

174.  Scouring  Effect  of  Falling  Water    183 

175.  Weir  Aprons 183 

176.  Rollerway  and  Ogee-shaped  Weirs 185 

177.  Water-cushions 186 

178.  Masonry  Weirs , 188 

179.  Masonry  Weirs  founded  on  Piles 190 

180.  Masonry  Weir  founded  on  Piles  and  Cribs 191 

181.  Masonry  Weir  founded  on  Cribs 192 

182.  Masonry  Weirs  founded  on  Wells 192 

183.  Concrete  Weir,  Ashlar  Facing    194 

184.  Rubble  Masonry  Weir 195 

185.  IronNOgee  Rollerway  Weir 196 

186.  Masonry  and  Iron  Drop-gate  Weir 196 

187.  Reinforced  Concrete  Weir ~ 200 

188.  Reinforced  Rubble  Masonry  Weir 202 

189.  Other  Masonry  Weirs    206 

190.  Diversion  Dams 208 

191.  River  Training  Works .  ." .  .   209 

CHAPTER  XI 

SLUICEWAYS,    REGULATORS,    AND    ESCAPES 

192.  Sluiceways 211 

193.  Examples  of  Sluiceways 212 

194.  Yuma  Project  and  Sluiceways,  Laguna  Weir 214 

195.  Sluice  Gates,  Laguna  Weir 217 

196.  Sluice  Gates,  Granite  Reef  Weir 219 


CONTENTS  xvii 

ARTv  PAGE 

.197.  Falling  Sluice-gates .  221 

198.  Bear-trap  Movable  Sluice-gates 221 

199.  Mahanuddy  Sluice  Shutters 223 

200.  Soane  Falling  Sluice-gates 224 

201.  Automatic  Wasteway  Gate 226 

202.  Relation  of  Weirs  to  Regulators    227 

203.  Granite  Reef  Regulator 229 

204.  Classification  of  Regulators 230 

205.  General  Form  of  Regulator    230 

206.  Arrangement  of  Canal  Head    231 

207.  Wooden  Flashboard  Regulators 232 

208.  Wooden  Gate  Lifted  by  Windlass 234 

209.  Gate  Lifted  by  Travelling  Winch 235 

210.  Gate  Raised  by  Gearing  or  Screw 235- 

211.  Inclined,  Horizontally  Pivoted  Falling  Gates    236 

212.  Hydraulic  Lifting  Gate 239 

213.  Wasteways   239 

214.  Location  and  Characteristics  of  Waterways 240 

215.  Design  of  Escape  Heads 242 

216.  Wasteways,  Reclamation  Service 244 

217.  Taintor  Circular  Wasteway  Gates 246 

218.  Sand-gates 250 


CHAPTER  XII 

FALLS    AND    DRAINAGE    WORKS 

219.  Excessive  Slope 255 

220.  Falls  and  Rapids    255 

221.  Retarding  Velocity  by  Flashboards  on  Fall  Crest    256 

222.  Retarding  Velocity  by  Contracting  Channel 257 

223.  Gratings  to  Retard  Velocity  of  Approach 257 

224.  Notched  Fall  Crest 260 

225.  Vertical  Fall  of  Wood 263 

226.  Masonry  Falls 264 

227.  Wooden  Rapids  or  Chutes   264 

228.  Masonry  Rapids 266 

229.  Drainage  Works 266 

230.  Drainage  Cuts 268 

231.  Inlet  Dams 268 

232.  Level  Crossings 270 

233.  Flumes -. 272 

234.  Sidehill  Flumes 274 

235.  Construction  of  Flumes 274 

236.  Stave  and  Binder  Flumes 275 

237.  Flume  Trestles 276 


xviii  CONTENTS 

ART.  PAGE 

238.  Iron  Aqueducts 276 

239.  Masonry  Aqueducts 279 

240.  Reinforced  Concrete  Flumes  and  Aqueducts 283 

241.  Superpassages 284 

242.  Culverts  and  Inverted  Siphons    289 

243.  Wooden  Culvert    291 

244.  Inverted  Siphons  of  Masonry 291 

245.  Reinforced  Concrete  Culverts 294 

246.  Reinforced  Concrete  Siphons 294 


CHAPTER  XIII 

DISTRIBUTARIES 

247.  Object  and  Types 296 

248.  Location  of  Distributaries 296 

249.  Design  of  Distributaries    297 

250.  Efficiency  of  a  Canal 299 

251.  Dimensions  of  Laterals 302 

252.  Capacities  of  Laterals    302 

253.  Distributary  Channels  in  Earth 303 

254.  Wooden  Lateral  Heads  and  Turnouts    304 

255.  Masonry  Lateral  Heads 310 

256.  Works  of  Reference:   Diversion  and  Canal  Works    311 


CHAPTER  XIV 

APPLICATION   OF   WATER,   AND   PIPE   IRRIGATION 

257.  Relation  of  Water  to  Plant-growth 313 

258.  Relation  of  Soil  Texture  to  Plant-growth 315 

259.  Theory  of  Cultivation  by  Irrigation    319 

260.  Methods  of  Applying  Water 321 

261.  Preparation  of  Ground  for  Irrigation 322 

262.  Sidehill  Flooding  of  Meadows   .  .  .  v 324 

263.  Flooding  by  Checks 325 

264.  Flooding  by  Checkerboard  System  of  Squares 326 

265.  Flooding  by  Terraces 327 

266.  Furrow  Irrigation  of  Vegetables  and  Grain 327 

267.  Combined  Flooding  and  Furrow  Irrigation  of  Orchards 328 

268.  Irrigating  Orchards  by  Small  Furrows 330 

269.  Ditch  and  Furrow  Checks    333 

270.  Subsurface  Irrigation  334 

271.  Subirrigation   Pipes 336 

272.  Main  and  Distributing  Pipes 336 


CONTENTS  xix 

ART.  PAG* 

273.  Flow  of  Water  in  Pipes 338 

274.  Formulas  of  Flow  in  Pipes  .  .   339 

275.  Tables  of  Flow  in  Pipes  with  and  without  Pressure    .   340 

276.  Sheet-iron  and  Steel  Pipes  ...  -   343~ 

277.  Wooden-stave  Pipes •   34° 

278.  Construction  of  Wooden  Pipe  Lines  ...  -347 

279.  Reinforced  Concrete  Pipe  •   349 

280.  Measurement  of  Flow  in  Pipes    •   35° 

281.  Works  of  Reference:   Application  of  Water  and  Pipe  Irrigation 352 


PART    III 

STORAGE  RESERVOIRS 

CHAPTER  XV 

LOCATION   AND   CAPACITY   OF   RESERVOIRS 

282.  Classes  of  Storage  Works    .353 

283.  Character  of  Reservoir  Site .   353 

284.  Relation  of  Reservoir  Site  to  Land  and  Water  Supply   354 

285.  Topography  and  Survey  of  Reservoir  Sites .   355 

286.  Exploring  for  Rock  Foundation -357 

287.  Geology  of  Reservoir  Sites    359 

288.  Cost  and  Dimensions  of  some  Great  Storage  Reservoirs    .  .   360 

289.  Classes  of  Dams .  360 

CHAPTER  XVI 

EARTH   AND   LOOSE-ROCK   DAMS 

290.  Earth  Dams  or  Embankments 365 

291.  Causes  of  Failure  of  Earth  Dams 365 

292.  Dimensions  of  Earth  Dams    365 

293.  Foundations 365 

294.  Foundations  of  Masonry  Core  and  Puddle  Walls 366 

295.  Springs  in  Foundations 366 

296.  Masonry  Cores,  Puddle  Walls,  and  Homogeneous  Embankments    367 

297.  Masonry  Core-walls  in  Earth  Embankments 369 

298.  Puddle  Walls  and  Faces 370 

299.  Puddle  Trench    371 

300.  Homogeneous  Earth  Embankment 372 


xx  CONTENTS 

ART.  PAGE 

301.  Embankment  Material 376 

302.  Embankment  of  Sand 377 

303.  Hydraulic-fill  Dam 377 

304.  Combined  Earth  and  Hydraulic-fill  Dam 378 

305.  Interior  Slope  and  Paving 380 

306.  Earth  Embankment  with  Masonry  Retaining-wall 382 

307.  Earth  and  Loose-rock  Dams — Pecos  Dam 383 

308.  Minidoka  Project  and  Dam,  Idaho 385 

309.  Loose-rock  Dams 387 

310.  Walnut  Grove  Dam 389 

311.  Rock -filled  Steel-core  Dam 391 

312.  Crib  Dams 392 

313.  Loose-rock  Dams  with  Masonry  Retaining-walls 394 

314.  Failure  and  Faulty  Design  of  Earth  and  Loose-rock  Dams 396 


CHAPTER  XVII 

MASONRY    DAMS 

315.  Theory  of  Masonry  Dams 399 

316.  Stability  of  Gravity  Dams 400 

317.  Stability  against  Sliding 402 

318.  Coefficient  of  Friction  in  Masonry 403 

319.  Stability  against  Crushing 404 

320.  Limiting  Pressures 406 

321.  Stability  against  Overturning 406 

322.  Molesworth's  Formula  and  Profile  Type   409 

323.  Height  and  Top  Width  of  Dam 410 

324.  Profile  of  Dam 410 

325.  Stability  against  Upward  Water  Pressure;    also  Causes  of  Failure   411 

326.  Stability  against  Temperature  Changes 415 

327.  Curved  Masonry  Dams 415 

328.  Design  of  Curved  Dams 418 

329.  Wide-crested  or  Overfall  Dams 420 

330.  Design  of  Overfall  Dams    421 

331.  Foundations 424 

332.  Preparing  Foundations 424 

333.  Material  of  which  Constructed 426 

334.  Concrete 428. 

335.  Rubble  Masonry 430 

336.  Cement 430 

337.  Details  of  Construction 431 

338.  Waterproofing  Materials 434 

339.  Submerged  Dams  437 

340.  Construction  in  Flowing  Streams 438 

341.  Specifications  and  Contracts 440 


CONTENTS  xxi 

PACK 
ART. 

342.  Examples  of  Masonry  Dams    4 

343.  Furens  Dam,  France. . 

344.  Gran  Cheurfas  Dam,  Algiers   . 

345.  Tansa  Dam,  India   . 

346.  Bhatgur  Dam,  India    . 

347.  New  Croton  Dam,  New  York •   447 

348.  Periar  Dam,  India.  . 

349.  Beetaloo  Dam,  South  Australia   . 

350.  Remscheid  Dam,  Germany  . 

351.  San  Mateo  Dam,  California  . 

352.  Sweetwater  Dam,  California  •  •  •   452 

353.  Vyrnwy  Dam,  Wales 

354.  Assuan  Dam  and  Assiout  Weir,  Egypt  -457 

355.  Betwa  Dam,  India  .... 

356.  La  Grange  Dam,  California  . 

357.  Folsom  Dam,  California 

358.  Austin  Dam,  Texas   

359.  Overfall  Masonry  Dam,  Spier  Falls,  X.  Y.  . 

360.  Roosevelt  Dam,  Arizona 

361.  Shoshone  Dam,  Wyoming 

362.  Bear  Valley  and  Zola  Dams  . . 

363.  Upper  Otay  Dam,  California 4/4 

364.  Buttressed  and  Arched  Masonry  Walls.  . 

365.  Steel  Dam,  Ash  Fork,  Arizona  . . 

CHAPTER  XVIII 

WASTE  WAYS    AND   OUTLET    SLUICES 

366.  Wasteways 

367.  Character  and  Design  of  Wasteways    ...  482 

368.  Discharge  of  Waste  Weirs  .  .  4^2 

369.  Classes  of  Wasteways  ....  4&3 

370.  Shapes  of  Waste  Weirs.  . 

371.  Examples  of  Wasteways    . 

372.  Automatic  Shutters  and  Gates  4$8 

373.  Automatic  Drop-shutters  . 

374.  Automatic  Weir-gates 

375.  Stoney's  Balanced  Sluice-gate  ...  493 

376.  Undersluices 495 

377.  Examples  of  Undersluices 49° 

378.  Outlet  Sluices 49" 

379.  Gate-towers  and  Valve-chambers  .  .  498 

380.  Examples  of  Gate-towers  and  Outlet  Sluices    . 

381.  Electrically  Operated  Outlet  Gates,  Roosevelt  Dam 

382.  Unit  Cost  of  Construction 

383.  Works  of  Reference..  .Storage  Works 


xxn  CONTENTS 


CHAPTER  XIX 

PUMPING,    TOOLS,    AND   MAINTENANCE 
ART.  PAGE 

384.  Pumping  or  Lift  Irrigation 509 

385.  Motive  Power  and  Pumps 510 

386.  Choice  of  Pumping  Machines    512 

387.  Animal  Motive  Power 514 

388.  Windmills 515 

389.  Capacity  and  Economy  of  Windmills 516 

390.  Varieties  of  Windmills 519 

391.  Value  of  Windmills  as  Irrigating  Machines 523 

392.  Power  in  Falling  Water 524 

393.  Water-motors 526 

394.  Undershot  Water-wheels 527 

395.  Overshot  Water-wheels 531 

396.  Turbine  Water-wheels 532 

397.  Pelton  Water-wheels 534 

398.  Uses  of  Water-power 536 

399.  Water-pressure  Engines 537 

400.  Hydraulic  Rams 539 

401.  Hot-air,  Alcohol,  and  Gasoline  Pumping-engines 541 

402.  Pumping  by  Steam-power 543 

403.  Producer  Gas  Power   545 

404.  Energy,  Work,  and  Power    545 

405.  Centrifugal  and  Rotary  Pumps    546 

406.  Examples  of  Centrifugal  Pumping  Plants    550 

407.  Steam  Pumping-engines 551 

408.  Examples  of  Steam  Pumping  Plants 552 

409.  Cost  of  Various  Powers  and  of  Pumping 555 

410.  Pulsometers  and  Mechanical  Elevators 556 

411.  Irrigation  Tools 557 

412.  Scrapers 557 

413.  Grading-  and  Excavating-machines 559 

414.  Maintenance  and  Supervision 560 

415.  Sources  of  Impairment  of  Irrigation  Works 561 

416.  Inspection 562 

417.  Works  of  Reference.    Pumping  Machinery 562 


CHAPTER  XX 

RECLAMATION    SERVICE   OF   UNITED    STATES 

418.  The  Reclamation  Law 564 

419.  Scope  of  Reclamation  Law 567 

420.  Water  Users'  Associations 569 

421.  Specifications,  Roosevelt  Dam 573 

422.  Unit  Costs,  Reclamation  Service 584 


CONTENTS  xxiii 


TABLES 


I.  Extent  and  Cost  of  Irrigation 5 

II.  Precipitation  by  River  Basins 10 

III.  Precipitiation  by  States 12 

IV.  Stream  Discharge  and  Runoff 18 

V.  Depth  of  Evaporation,  in  inches  per  Month  in  1887-88 26 

VI.  Depth  of  Evaporation  per  Month,  in  inches 27 

VII.  Units  of  Measure 48 

VIII.  Duty  of  Water 51 

IX.  Value  of  V  in  feet  per  Second  and  of  C  for  Earth  Channels  by 

Kutter's  Formula    63 

X.  Grades,  Slopes,  and  Values  A  i  in  Kutter's  Formula    65 

XL  Values  of  A,  r,  and  \/r  for  Rectanglar  Channels 66 

XII.         "       "        "       "       "     "  Side  Slopes  of  i  on  i    67 

XIII.  "       "        "       "       "     "       "         "       "  i  on  ij    63 

XIV.  "       "  C  for  given  Slopes  and  Hydraulic  Mean  Radii 69 

XV.  Discharge  over  Rectangular  Weirs 81 

XVI.  Discharge  over  Cippoletti  Trapezoidal  Weir 83 

XVII.  Some  Great  Perennial  Canals 1 24 

XVIII.  Values  of  K  in  Flynn's  Kutter  Formula 342 

XIX.  Values  of  \/f  for  Circular  Pipes    342 

XX.  Factors  for  use  in  D'Arcy's  Formula  of  Flow  through  Clean  Pipes  343 
XXL  Factors  for  use  in  D'Arcy's  Formula  of  Flow  through  Tuberculated 

Pipes..                                                                                                     .    344 
XXII.  Values  of  C\/r  in  Flynn's  Kutter  Formula 344 

XXIII.  Cost  and  Dimensions  of  some  Storage  Reservoirs    361 

XXIV.  Coefficients  of  Friction  in  Masonry 403 

XXV.  Wegmann's  Practical  Profile  No.  3  413 

XXVI.  Wind  Velocity  and  Power 516 

XXVII.  Capacity  of  Windmills 517 

XXVIII.  Energy  of  Wind  Acting  upon  a  Surface  of  100  Square  Feet    ....   519 

XXIX.  Capacities  and  Efficiencies  of  Several  Windmills    520 

XXX.  Equivalent  Units  of  Energy 546 

XXXI.  "     "   Work 546  - 

XXXII.  "  "     "   Power 547 


ILLUSTRATIONS 


LIST   OF    PLATES 

PLATE  PAGE 

I.  Plan  and  Cross-section  of  Ganges  Canal,  Hurdwar  to  Roorkee, 

India 137 

II.  Mill  Creek  Flume  and  Steel  Bridge,  Santa  Ana  Canal    145 

III.  View  on  Line  of  Santa  Ana  Canal    14; 

IV.  Kern  River  Diversion  Weir.     Head  of  Calloway  Canal 169 

V.  Cross-sections  of  Indian  Weirs 171 

VI.  View  of  Old  Weir  and  Scouring  Sluices,  Head  of  Arizona  Canal. 

VII.  Cross-section  of  Croton  Dam 

VIII.  Iron-faced  Rollerway  Weir,  Cohoes,  X.  Y 107 

IX.  Granite  Reef  Weir,  Salt  River,  During  Construction 20^ 

X.  View  of  Goulburn  Weir,  Australia 207 

XL  Falling  Sluice-gate,  Soane  Canal,  India 22  > 

XII.  Bear  River  Canal.    Elevation  and  Cross-section  of  Weir  and  Reg- 
ulator    238 

XIII.  Cross-section  and  Elevation  of  Regulator  Gates,  Folsom  Canal ....  243 

XIV.  Plan  of  Rapids,  Bari  Doab  Canal,  India 267 

XV.  Highline  Canal,  Colorado.     View  of  Bench  Flume 273 

XVI.  View  of  Solani  Aqueduct,  Ganges  Canal,  India 280 

XVII.  View  of  Ranipur  Superpassage,  Ganges  Canal,  India   287 

XVTII.  Idaho  Irrigation  Company's  Canal.     View  of  Wooden  Siphon  on 

Phyllis  Branch 288 

XIX.  Rawhide  Siphon,  Interstate    Canal.     A.  Inlet,  B.  Creek  Bed.  .  .  .  293 

XX.  Standard  Masonry  Outlet  for  Distributaries,  Punjab,  India 307 

XXI.  Irrigating  Orchard  by  Terraced  Basins  on  Hillside   329 

XXII.  Earth  Dam  and  Masonry  Core-wall  during  Construction,  Carmel, 

N.  Y " 375 

XXIII.  Lower  Otay  Rock-filled  Dam 393 

XXIV.  Excavating  Foundation  for  New  Croton  Dam  and  Gate-house  .  .  427 
XXV.  View  of  Bhatgur  Dam,  India  445 

XXVI.  San  Mateo  Dam.    Plan,  Cross-section,  and  Outlet  Sluices 45 1 

XXVII.  Plan  of  Sweetwater  Dam 453 

XXVIII.  Cross-section  of  Sweetwater  Dam    454 

XXIX.  View  of  Sweetwater  Dam    455 

XXX.  Folsom  Canal,  View  of  Weir  and  Regulator •      .  461 

XXXI.  Folsom  Canal,  Plan  and  Cross-section  of  Weir  ...  .  463 

XXXII.  Plan  of  Roosevelt  Dam,  Salt  River  Project,  Arizona 4^7 


xxvi  ILLUSTRATIONS 

PLATE  PAGH 

XXXIII.  Maximum  Cross-section,  Roosevelt  Dam,  Arizona 469 

XXXIV.  Upper  Otay  Masonry  Dam 475 

XXXV.  View  of  New  Croton  Dam  and  Wasteway 485 

XXXVI.  Reinold's  Automatic  Waste  Gate,  India 492 

XXXVII.  Vertical  Lift  Outlet  Gate,  Fay  Lake  Reservoir,  Arizona 501 

XXXVIII.  Outlet  Gates,  Roosevelt  Dam,  Arizona 505 


LIST   OF   ILLUSTRATIONS 

FIG. 

1.  Rain  Gauge 14 

2.  Relation  of  Runoff  to  Rainfall 15 

3.  Evaporating-pan 24 

4.  Price  Electric  and   Acoustic  Current  Meters 71 

5.  Haskell  Current  Meter 72 

6.  Price  Acoustic  Current  Meter    73 

7.  Cable  Station,  Car,  Gauge,  etc 75 

8.  Rectangular  Measuring  Weir  78 

9.  Foote's  Measuring  Weir,  A.    Water  Divisor,  B   86 

10.  Australian  Water  Meter    87 

11.  Portable  Artesian-well  Drilling  Rig 99 

12.  Pumping  Station  and  Group  of  Wells,  Garden  City,  Kan 104 

13.  Subterranean  Water  Tunnel  and  Feed  Wells    106 

14.  Gathering  Cribs,  Citizen's  Water  Co.,  Denver 108 

15.  Canal  Cross-sections  for  Varying  Bed-widths 133 

16.  Turlock  Canal.    Plan  of  Diversion  Line 139 

17.  Turlock  Canal.    View  of  Sidehill  Work 140 

18.  Tunnel  on  Truckee  Carson  Canal,  Nevada 148 

19.  Various  Canal  Cross-sections 153 

20.  Cross-section  of  Calloway  Canal,  showing  Subgrade   155 

21.  Typical  Section  of  Lined  Canal,  Reclamation  Service 155 

22.  Cross-section  of  Lined  Channel,  Santa  Ana  Canal    156 

23.  Concrete  Lining,  Truckee -Carson  Canal,  Nevada 157 

24.  Reinforced  Concrete  Canal  Lining,  Tieton  Canal 158 

25.  Plan  and  Cross-section  of  Sheet  Steel  Irrigation  Canal,  Upper  Egypt.  ...  159 

26.  Rock  Cross-section,  Turlock  Canal 160 

27.  A.  Rock  Cross-section,  Bear  River  Canal.    B.  Umatilla  Canal 160 

28.  Transition  from  Rock  to  Earth  Cross-section 161 

29.  Cross-section  of  Open  Weir,  Calloway  Canal 170 

30.  Half -elevation  and  Plan,  and  Section  of  Soane  Weir,  India 173 

31.  Elevation  and  Cross-section  of  Sidhnai  Weir,  India    174 

32.  Cross-section  of  Laguna  Weir,  Colorado  River 176 

33.  View  of  Open  Weir  on  River  Seine,  France 177 

34.  Rolling  Lift  Weir,  Schweinfurt,  Bavaria    178 

35.  Cross-section  of  Old  Arizona  Weir   180 

36.  Cross-section  of  Bear  River  Weir    182 

37.  Cross-section  of  Old  Holyoke  Weir 183 


ILLUSTRATIONS  xxvii 

FIG.  PAGB 

38.  Cross-section  of  Lower  Yellowstone  Weir,  Mont 184 

39.  Diagram  of  Ogee  Curve   ^5 

40.  Cross-sections  of  Eight  Ogee -shaped  Weirs 186 

41.  Leasburg  Diversion  Weir,  Rio  Grande  Project,  N.  M 190 

42.  Cross-section  of  Norwich  Water  Power  Company's  Weir 191 

43.  Cross-section  of  Henares  Weir,  Spain 194 

44.  Cross-section  of  Iron  Weir,  Cohoes,  N.  Y 195 

45.  Down-stream  Elevation,  Goulburn  Weir,  Australia 198 

46.  Section  of  Goulburn  Weir,  Australia    199 

47.  Cross-section  of  Reinforced  Concrete  Weir,  Theresa,  N.  Y 200 

48.  Cross-section  of  Corbett  Dam,  Shoshone  Project,  Wyo 201 

49.  Plan  and  Section  of  Corbett  Dam  and  Headworks 202 

50.  Plan  of  Granite  Reefs  Weir  and  Headworks 203 

51.  Cross-section  of  Granite  Reefs  Weir,  Arizona 204 

52.  Granite  Reefs  Weir  and  Apron  on  Bowlder  Foundation 206 

53.  Cross-sections  of  Newark  Dam  and  Weir   208 

54.  Cross-section  of  New  Holyoke  Weir,  Mass 209 

55.  Plan  of  Headworks,  Laguna  Weir,  Colorado  River 213 

56.  Plan  of  Headworks,  Granite  Reef  Weir,  Salt  River,  Arizona 215 

57.  Sluice  Gate  with  Operating  Machinery,  Laguna  Weir   216 

58.  Half  Plan,  Sluice  Gate,  Laguna  Weir 217 

59.  Operating  Mechanism,  Sluice  Gates,  Granite  Reefs  Weir 219 

60.  Rear  of  Sluice  Gate,  Granite  Reefs  Weir 220 

61.  Chanoine  Movable  Shutters,  Raised,  Lowered,  and  Closed  222 

62.  Bear-trap  Gate.    Parker  Modification 223 

63.  Cross-section  of  Mahanuddy  Automatic  Shutters,  India 224 

64.  Automatic  Wasteway  Gate,  Belle  Fourche    227 

65.  Plan  of  Headworks,  Ganges  Canal,  India 228 

66.  Plan  of  Old  Headworks,  Arizona  Canal 229 

67.  Regulator  Gates,  Laguna  Weir,  Colorado  River 233 

68.  Regulator  Gates,  Ganges  Canal 234 

69.  Regulator  Gates,  Soane  Canal,  India 234 

70.  Wooden  Lever  and  Screw  Regulator  Gates 235 

71.  Regulator  Gate,  Leasburg  Canal,  Rio  Grande 236 

72.  Wooden  Gate,  Leasburg  Canal  Regulator 237 

73.  Regulator  Gate,  Minidoka  Canal,  Idaho 237 

74.  Inclined,  Falling  Regulator  Gates,  Goulburn  Canal,  Australia  241 

75.  Escape-flume  on  Goulburn  Canal,   Australia 244 

76.  Spillway,  Fort  Shaw  Canal,  Montana 245 

77.  Standard  Sluiceway,  Lower  Yellowstone  Canal    245 

78.  Pine  Ridge  Sluiceway,  Interstate  Canal 246 

79.  By-pass  Feeder  Weir,  Umatilla  Canal    247 

50.  Wasteway  and  Taintor  Gates,  Lower  Truckee  Canal 249 

51.  Cross-section  of  Sand  Box,  Santa  Ana  Canal 250 

£2.  Standard  Sluice  Gates,  Lower  Yellowstone  Canal 251 

83.  Cast-iron  Sluice  Gate,  Interstate  Canal,  Neb.-Wyo 252 

£4.  Sand-gate,  Leasburg  Canal,  Rio  Grande 253 


xxviii  ILLUSTRATIONS 

FIG.  PAGE 

85.  Section  of  lo-foot  Fall  with  Grating  and  Water  Cushion 258 

86.  Typical  Fall  with  Grating,  Uncompahgre  Canal 259 

87.  Notched  Fall,  Interstate  Canal,  Neb.-Wyo 260 

88.  Notched  Fall,  Chenab  Canal,  India 261 

89.  Cross-section  of  Fall,  Bear  River  Canal 262 

90.  Timber  Drop,  Lower  Yellowstone  Lateral    263 

91.  Concrete  Fall  with  Water  Cushion 264 

92.  Kushuk  Fall,  Agra  Canal,  India 265 

93.  Plan  and  Elevation  of  Big  Drop,  Grand  River  Canal 265 

94.  Reinforced  Concrete  Rapid,  Okanogan,  Wash 269 

95.  Pipe  Inlet,  Reno  Coulee,  Lower  Yellowstone  Canal    269 

96.  Plan  of  Rutmoo  Crossing,  Ganges  Canal,  India    .  . 271 

97.  Cross-section  of  San  Diego  Flume 275 

98.  Cross-section,  Stave  and  Binder  Flume,  Santa  Ana  Canal 276 

99.  Standard  Timber  Flume  and  Trestle,  Reclamation  Service 277 

100.  Elevation  and  Cross-section  of  Iron  Flume,  Bear  River  Canal 278 

joi.  Aqueduct,  Henares  Canal,  Spain 279 

102.  Nadrai  Aqueduct,  Lower  Ganges  Canal,  India 281 

103.  Standard  Reinforced  Concrete  Flume  and  Trestle,  Reclamation   Service  282 

104.  Circular  Reinforced  Concrete  Flume  and  Trestle 283 

105.  Longitudinal  Section,  Reinforced  Concrete  Aqueduct,  Interstate  Canal.  .    284 

106.  Section  through  Reinforced  Concrete  Aqueduct,  Interstate  Canal 285 

107.  Reinforced  Concrete  Aqueduct  Spring  Canyon,  Interstate  Canal 286 

108.  Section  of  Wooden  Culvert,  Del  Norte  Canal,  Colorado 289 

109.  Soane  Canal.     Cross-section  of  Kao  Nulla  Siphon-aqueduct 290 

no.  Section  of  Sesia  Siphon,  Cavour   Canal,   Italy 290 

in.  Reinforced  Concrete  Culvert,  Lower  Yellowstone  Canal 291 

112.  Reinforced  Concrete  Twin  Siphon,  Yellowstone  Canal ..... .  .    292 

113.  Reinforced  Concrete  Twin  Siphon,  Interstate  Canal 294 

114.  Diagram  Illustrating  Distributary  System 297 

115.  Distributary  System,  Huntley  Canal,  Mont 298 

116.  View  of  Distributary  Head,  Calloway  Canal 304 

117.  Wooden  Turnout,  Sun  River  Canal,  Mont 305 

1 18.  Reinforced  Concrete  Turnouts  for  Laterals 306 

119.  Reinforced  Concrete  Turnouts  for  Laterals  with  Drop 308 

120.  Cast  Iron  Gates  for  Laterals,  Interstate  Canal  , 309 

121.  Wooden  Gates  for  Laterals,  Interstate  Canal 310 

122.  Diagram  Illustrating  Flooding  of  Meadows 324 

123.  Irrigation  by  System  of  Check-levees 325 

124.  Flooding  by  System  of  Squares 326 

125.  Furrow  Irrigation  of  Grain 328 

126.  Furrow  Irrigation  of  Orchards 330 

127.  Extent  of  Percolation  from  Small  Furrows    ...... ...   332 

128.  Using  Canvas  Dam 333 

129.  Steel  Dams 334 

130.  Flow  of  Water  in  Pressure  Pipe 338 

131.  Traveling  Forms  for  Moulding  Concrete  Pipe .........   349 


ILLUSTRATIONS  xxix 

FIG.  PAGE 

132.  Venturi  Meter  and  Recording  Device 35 1 

133.  Diagrams  Illustrating  Geology  of  Reservoir  Site 360 

134.  Cold  Springs  Dam,  Umatilla  Project,  Ore 369 

135.  Cross-section  of  Titicus  Earth  Dam,  N.  Y 370 

136.  Core-wall  and  Earth  Embankment,  Boston   Water- works 370 

137.  Earth  Dam  with  Puddle  Face,  Monument  Creek,  Col 371 

138.  Ashti  Dam,  India,     Cross-section 373 

139.  Cross-section  of  Earth  Dam,  Santa  Fe,  showing  Masonry  Cross-Trenches  373 

140.  San  Leandro  Earth  and  Hydraulic-fill  Dam   379 

141.  Section  and  Paving,  Belle  Fourche  Dam,  S.  D 381 

142.  Cross-sections  of  Kabra  Dam  (A)  and  Ekruk  Dam  (B),  India    382 

143.  Cross-section  of  Pecos  Dam   384 

144.  Avalon  Dam,  Carlsbad  Project,  X.  M 384 

145.  Dam,  Regulator,  and  Headworks,  Minidoka  Project,  Idaho 385 

146.  Cross-section,  Rock-fill  Dam,  Minidoka  Project,  Idaho 386 

147.  Cross-section,  Concrete  Waste  Weir,  Minidoka  Project,   Idaho 387 

148.  Elevation  and  Cross-section  of  Walnut  Grove  Dam 390 

149.  Rock-filled  Steel-core  Dam,  Lower  Otay,  Cal 391 

150.  Plan  and  Cross-section  of  Bowman  Dam    395 

151.  Elevation,  Plan,  and  Cross-section  of  Castlewood  Dam 396 

152.  Theoretical  Triangular  Cross-section  of  Dam 402 

153.  Diagram  illustrating  Wegmann's  Formula 407 

154.  Molesworth's  Profile  Type    411 

155.  Comparison  of  Profile  Types 412 

156.  Practical  Profile  from  Wegmann   417 

157.  Flow  over  Wide-crested  Dam 423 

158.  Steel  Forms,  McCall's  Ferry  Dam,  Penn 429 

159.  View  of  San  Fernando  Submerged  Dam 438 

160.  Cross-section  of  Furens  Dam,  France 441 

161.  Cross-section  of  Gran  Cheurfas  Dam,  Algiers    442 

162.  Cross-section  of  Tansa  Dam,  India    443 

163.  Cross-section  of  Bhatgur  Dam,  India 446 

164.  Cross-section  of  Masonry  Dam,  New  Croton  Dam,  Cornell's 447 

165.  Cross-section  of  Overfall  Weir,  New  Croton  Dam,  Cornell's 448 

166.  Cross-sections  of  Periar  Dam,  India 449 

167.  Cross-section  of  Beetaloo  Dam,  Australia   450 

168.  Cross-section  of  Vyrnwy  Dam,  Wales 456 

169.  Cross-sections  of  Assuan  Dam,  Egypt    458 

170.  Cross-section  of  Betwa  Dam,  India    459 

171.  Cross-section  of  La  Grange  Dam    460 

172.  Cross-section  of  Austin  Dam    464 

173.  Spier  Falls  Dam,  N.  Y 465 

174.  Overfall  Section,  Spier  Falls  Wreir,  N.  Y 466 

175.  Cross-section  of  Shoshone  Dam,  Wyo 471 

176.  Cross-section  of  Bear  Valley  Dam,  Cal 472 

177.  Plan  and  Elevation  of  Bear  Valley  Dam,  Cal 472 

178.  Sections  of  Arched  Masonry  Dams 473 


xxx  ILLUSTRATIONS 

FIG.  PAGE 

179.  Meer  Allum  Dam,  India : 476 

180.  East  Park  Dam  and  Spillway,  Orland  Project,  Cal 477 

181.  Steel  Dam,  Ash  Fork,  Arizona 479 

182.  Plan  of  Santa  Fe  Reservoir,  Wasteway    and   Waste-weir 487 

183.  Cross-section  of  Shutter  on  Soane  Weir,  India 488 

184.  Automatic  Drop-shutter,  Betwa  Weir,  India 489 

185.  Attachment  of  Tension-rod  to  Drop-shutter   490 

186.  Stoney's  Balanced  Sluice-gate,  Periyar  Dam,  India 494 

187.  Outlet  Pipes  in  Earth  Dam    498 

1 88.  Valve-plugs,  Sweetwater  and  Hemet  Dams 499 

189.  Valve-chambers,  Wachusett  Dam,  Boston 502 

190.  Gate  House,  Conconully  Dam,  Wash 503 

191.  Diagram  for  Determining  Horse-power  of  Water-wheels  and  Water-falls  525 

192.  Undershot  Water-wheel  or  Noria ...  529 

193.  Floating  Pumping  Station,  Williston,  N.  D 554 

194.  Buck  Scraper 558 

195.  New  Era  Excavator 559 


IRRIGATION    ENGINEERING 


CHAPTER  I 

INTRODUCTION 

i.  Meaning  of  Irrigation. — The  word  irrigation  implies  a 
condition  far  more  imposing  than  is  intended.  In  dry  weather 
a  watering-pot  is  used  to  sprinkle  such  plants  and  flowers  as  are 
considered  most  valuable,  or  perhaps  a  hose  or  water-barrel  is 
used  to  moisten  more  or  less  of  the  garden  truck.  This  is  irrigation 
pure  and  simple.  The  only  difference  between  this  form  and 
that  more  generally  implied  by  the  word  irrigation  as  used  in  arid 
lands  is  that  in  the  latter  the  application  of  water  to  crops  becomes 
a  business,  and  the  farmer  and  the  engineer  unite  in  the  employ- 
ment of  methods  whereby  water  may  be  applied  in  the  easiest, 
least  expensive,  and  most  certain  manner.  This  is  by  the  action 
of  gravity,  and  irrigation  by  natural  flow  is  the  result.  Ditches 
are  constructed  which  lead  the  water  from  the  source  of  supply, 
be  it  well,  reservoir,  or  stream;  and  they  are  so  aligned  and  graded 
that  the  water  shall  flow  through  these  and  from  them  into  minor 
channels,  and  from  these  again  be  led  by  ploughed  or  drilled 
furrows  through  the  fields. 

The  mistake  is  too  commonly  made  of  regarding  the  work 
of  irrigation  as  a  hardship,  and  the  necessity  for  it  as  a  misfortune. 
In  point  of  fact,  the  necessity  for  irrigation  and  the  ability  to 
irrigate  make  a  fortunate  combination.  They  imply  a  warm, 
dry  climate,  as  that  of  the  arid  regions ;  and  this  means  that  the 
crops  are  not  liable  to  destruction  by  sudden,  violent  storms  or 
by  the  lack  of  sufficient  sunshine  or  by  the  failure  of  water-supply, 
as  sometimes  results  from  dependence  upon  rainfall  alone.  All 
of  this  fortunate  combination  is  not  found  in  the  semi-humid 
region,  where  the  rainfall  is  generally  sufficient  for  the  maturing 


2  INTRODUCTION 

of  crops.  As  a  result  there  is  not  the  ever-present  sunshine  and 
immunity  from  damaging  storms,  yet  here  irrigation  may  fulfil 
one  of  its  most  important  functions — that  of  helping  Nature  through 
the  drought  periods,  or,  in  other  words,  that  of  an  insurance  on 
the  crops. 

2.  Extent    of    Irrigation. — The    extent    to    which    irrigation 
can  be  practised  is  enormous.     The  total  area  irrigated  in  India 
is  about  40,000,000  acres,  in  Egypt  about  6,000,000  acres,  and  in 
Italy  about  4,700,000  acres.     In  Spain  there  are  2,800,000  acres, 
in  France  400,000  acres,  and  in  the  United  States  nearly  10,000,000 
acres  of  irrigated  land.     This  means  that  in  these  countries  alone 
crops  are  grown  on  63,900,000  acres  of  land  which  but  for  irrigation 
would  be  barren  and  unproductive.     In  addition  there  are  some 
millions  more  of  acres  cultivated  by  the  aid  of  irrigation  in  China, 
Japan,  Australia,  Algeria,  South  America,  and  elsewhere. 

The  works  which  provide  water  for  the  irrigation  of  the 
63,900,000  acres  above  specified  represent  an  investment  of  about 
$700,000,000,  and  the  area  thus  rendered  culturable  yields  annually 
products  valued  at  about  $725,000,000.  This  represents  an 
interest  on  the  original  investment  which  seems  absurd,  but  in 
fact  it  means  only  that  the  yield  of  irrigated  crops  averages  about 
$11.30  per  acre  controlled.  There  are  invested  in  irrigation 
works  in  the  United  States  $100,000,000,  and  in  India  $390,000,000. 

3.  Control   of  Irrigation  Works. — The  development   of   irri- 
gation has  resulted  in  many  legal  complications,  while  a  diversity 
of  social  and  physical  conditions  has  given  rise  to  a  variety  of 
methods  for  its  control.     Practically  all  the  works  in  India  are 
under  the  direct  control  of  the  government,  which  employs  its 
engineers  and  legal  staff,  owns  the  land  and  the  water,  constructs 
the  works,  and  collects  the  rentals  for  the  use  of  water  and  land. 
In  the  Piedmont  valley  of  Italy  the  land  is  the  property  of  in- 
dividuals, and  in  some  cases  individuals  are  owners  of  the  irrigation 
works.     In  the  case  of  the  Cavour  canal,  however,  the  government 
owns  and  operates  the  works,  and  the  water  is  sold  to  the  cultivators, 
In  the  United  States  the  greater  portion  of  the  irrigation  works 
are  the  property  of  individuals,   corporations,   or  communities, 
who  construct  and  maintain  them  and  collect  the  rentals  for  the 


VALUE    AS    AN    INVESTMENT  3 

use  of  water.  In  some  cases  the  same  individual  owns  both  land 
and  water;  but  usually  farmers  and  irrigators  have  no  property 
interest  in  the  irrigation  works.  These  are  owned  and  operated 
by  independent  organizations  who  collect  a  revenue  from  the  sale 
or  rental  of  water.  A  few  properties  are  State-built  or  owned  by 
the  States. 

The  United  States  government  has  recently  embarked  upon 
the  policy  of  constructing  and  operating  irrigation  works  under 
the  direction  of  the  Secretary  of  the  Interior,  through  the  medium 
of  the  Reclamation  Service.  In  the  first  five  years  of  its  exist- 
ence this  organization  has  expended  nearly  $43,000,000  on  great 
irrigation  works  which  will  reclaim  several  million  acres  of  land. 

4.  Value  as  an  Investment. — As  an  investment  irrigation 
works  are  not  always  successful.  There  should  be  a  ready  market 
for  the  products  of  irrigation,  and  the  interest  charges  on  land  and 
water  must  not  be  so  great  as  materially  to  reduce  the  profits 
from  crops.  The  value  of  irrigation  as  an  investment  is  especially 
dependent  on  the  humidity  of  the  climate.  In  a  semi-humid 
region,  where  during  occasional  seasons  the  nunfall  is  sufficient 
to  mature  the  crops,  there  is  but  an  intermittent  demand  for  water 
for  irrigation,  and  consequent  irregular  return  derived  from  its 
sale.  In  an  arid  region,  where  crops  cannot  be  raised  without  the 
aid  of  irrigation,  the  demand  for  water  is  constant.  In  the  northern 
provinces  of  India  water  is  in  constant  demand  for  irrigation,  and 
it  returns  excellent  profits.  In  Bombay  and  other  places  where  the 
demand  for  water  is  intermittent,  because  the  rainfall  is  frequently 
sufficient  to  mature  crops,  irrigation  works  are  designated  as 
" protective"  (against  famine),  and  the  revenue  derived  from  them 
is  insufficient  to  pay  interest  and  working  charges.  Perhaps  the 
most  important  factor  bearing  on  this  subject  in  our  arid  regions 
is  the  degree  of  habitation.  Nearly  anywhere  that  a  good  market 
can  be  found  and  irrigation  is  essential  to  the  production  of  crops, 
fair  interest  can  be  obtained  on  money  invested  in  irrigation  works. 
Many  failures,  however,  have  occurred,  due  chiefly  to  the  lack 
of  population,  and  consequent  lack  of  demand  for  water.  Where 
all  the  water  furnished  is  utilized  economically  designed  works  al- 
most invariably  pay  fair  returns  on  the  investment. 


4  INTRODUCTION 

5.  Incidental  Values. — Not  only  is  the  direct  money  return 
from  an   irrigation  investment  to  be  considered,  but  there  are 
several  incidental  means  whereby  profit  may  be  derived  from  such 
investments.     On  broad  principles  of  general  government  and 
policy  the  construction  of  irrigation  works  is  of  benefit  to  the 
whole  country.     They  furnish  homes  and  agricultural  pursuits 
for  many  who  must  otherwise  be  idle  or  find  less  substantial 
support  in  other  ways.     Irrigation  adds  to  the  general  wealth  of 
the  country  by  increasing  the  amount  of  its  agricultural  products. 
It  furnishes  excellent  investment  for  capital  where  the  projects  are 
well  designed.     It  results  in  the  conversion  of  barren  and  desert 
lands  into  delightful  homes,  and  aids  in  the  general  development 
of  the  other  resources  of  the  region  in  which  it  is  practised,  as 
mining,  lumbering,  grazing,  etc.     One  of  the  great  advantages 
of  irrigation  is  that  it  becomes  practically  an  insurance  on  the 
production  of  crops.     Its  practice  may  not  be  necessary  in  the 
semi-humid  or  humid  regions,  but  even  there  occasional  droughts 
occur  and   crops  are  lost.     Where  an   irrigation   system   exists 
in  such  cases,  it  will  probably  be  called  into  requisition  once  or 
twice  in  the  course  of  the  year,  and  may  save  vast  sums  which 
would  otherwise  be  lost  by  the  destruction  of  crops. 

6.  Cost   and  Returns  of   Irrigation. — The   returns   of    irriga- 
tion vary  greatly  with  the  soil,  climate,  degree  of  aridity,  and  the 
nature  and  value  of  the  crops  which  can  be  grown.     Thus  in  the 
semi-humid  and  humid  regions  irrigation  may  serve  only  as  an 
insurance  on  the  crops  by  providing  against  possible  deficiencies 
in  rainfall.     In  Utah  and  neighboring  States  where  only  grain, 
hay,  potatoes,  and  kindred  crops  can  be  grown,  and  water  is  not 
economically  handled,   the  returns  from  irrigation  are  far  less 
than  in  southern  California  and  Arizona,  where  valuable  citrus 
fruits  can  be  cultivated.     From  a  number  of  experimental  crops 
grown  and  marketed  the  following  values  were  derived  for  each 
acre-foot  of  water  used  in  irrigating  them.     In  Montana,  $18.42; 
Utah,  $6.34;  Wyoming,  $7.69;  Arizona,  $3.37  to  $30;  California, 
$10  to  $237. 

The  table  on  p.  5,  compiled  from  the  reports  of  the  U.  S. 
Census  of  1900,  gives  an  excellent  idea  of  the  extent  and  cost  of 


INCIDENTAL    VALUES 


irrigation,  and  of  the  value  of  the  land  and  water  after  irrigation  has 
been  provided.  While  the  average  first  cost  of  water,  that  is,  the 
cost  of  constructing  canals  to  bring  the  water  to  the  land,  was  $7.80 
per  acre,  the  average  value  of  water  per  acre  as  estimated  by 

TABLE  I. 

EXTENT   AND    COST   OF   IRRIGATION. 


States. 

Acreage  in 
Crops. 

Average  size  of 
Irrigated  Farms, 
in  Acres.  ' 

Average 
Value  of 
Irrigated 
Land  per 
Acre. 

Average 
Value  of 
Products 
from 
Irrigated 
Land 
per  Acre 
per 
Annum. 

Average 
First  Cost 
of  Water 
per  Acre.2 

11. 

& 

fcpfc 

>0o. 

< 

Arizona  

177,271 

62 

$4?    co 

$16  40 

$o   ?o 

$0    82 

California       

^O/'*^^ 

1,026,832 

c6 

80  io 

•}  07 

IO    7O 

60 

Colorado  

1,300,840 

01 

4O    77 

1  1   40 

721 

2.4 

Idaho  

^07,067 

67 

71    2? 

io  67 

9r  i 

24 

Montana  

J     /'VVO 

?(;?,86q 

TI8 

io  66 

4   O2 

28 

Nevada  

327.22!; 

26? 

28   47 

8  82 

2  86 

18 

New  Mexico  

<*«'*'x  3 

182,804 

3 

26 

*°-4/ 
2O    26 

i  ?  01 

6  co 

82 

Oregon  '.  

280  041 

84 

21    6? 

IO    1  7. 

4    76 

22 

Utah     

577.C88 

•JC 

37    4C 

17  88 

91  7 

24 

Washington  

IOQ  52? 

TO 

ol  ••! 

48  8? 

2  1     C.6 

1  2    ?6 

^4 

Wyoming  

700.482 

T63 

16  io 

727 

6    <J7 

16 

Total             .... 

C.C7O  408 

71 

$42    ?  7 

$14    87 

$7    80 

So  78 

1  Average  size  of  irrigated  tracts. 

2  Not  including  cost  of  systems  obtaining  water  from  wells. 
8  Average  annual  ~ost  of  maintenance. 

the  owners  after  they  obtain  it  was  $26.  This  shows  clearly 'the 
inherent  value  which  the  mere  fact  of  possessing  the  water  gives 
to  it.  In  other  words,  the  water  is  so  scarce  and  valuable  of  itself 
as  to  increase  by  threefold  the  cost  of  making  it  available.  The 
average  value  of  the  land  before  irrigation  was  from  $2.50  to  $5 
per  acre,  while  the  same  land  after  a  water-supply  had  been  pro- 
vided was  valued  at  $42.53  per  acre,  and  the  products  from  this 
land  had  an  average  value  of  $14.87  per  acre,  which  represented 
an  unusually  large  interest  on  the  money  invested. 

The  cost  of  a  water-right  under  the  projects  of  the  Reclamation 
Service  (Art.  418),  varies  from  about  $30  to  $70  per  acre;  the  size 
of  a  farm  unit  from  20  to  160  acres;  and  the  annual  maintenance 
charge  for  use  of  water  from  40  cents  to  one  dollar. 


6  INTRODUCTION 

In  addition  to  the  5,570,498  acres  of  irrigated  crops  in  1900  there 
were  1,595,133  acres  in  pasture  and  unmatured  crops,  making  a 
total  of  7,539,545  acres  under  irrigation.  The  increase  in  area 
under  irrigation  in  the  United  States  during  the  previous  ten  years 
was  107.6  per  cent. 

Of  the  total  irrigated  area  in  crops,  the  total  value  of  the 
products  therefrom  was  $86,860,491,  while  the  total  cost  of  con- 
struction of  irrigation  works  in  operation  had  been  $67,770,942. 
This  represents  animal  interest  earned  on  the  capital  outlay  at 
the  rate  of  128  per  cent,  exclusive  of  working  expenses  and  costs 
of  cultivation,  interest  on  investment  in  farms,  etc.  In  1900  the 
total  number  of  irrigators  in  the  United  States  was  102,819.  The 
area  reported  irrigated  from  streams  or  reservoirs  was  7,093,629 
acres,  and  from  wells  169,644  acres. 

The  Sidhnai  canal,  India,  earned  26  per  cent  interest  on  the 
capital  outlay  in  1907;  the  Ganges  canal  9^  per  cent;  some  pro- 
tective works  as  low  as  4%;  and  the  entire  irrigation  system  of 
India,  productive  and  protective,  earned  a  net  income  of  7^  per 
cent. 


Part  One 
HYDROGRAPHY 


CHAPTER  II 

PRECIPITATION,    RUNOFF,   AND  STREAM-FLOW 

7.  Relation  of  Rainfall  to  Irrigation. — Where  climate  and  soil 
are  favorable  to  the  production  of  crops,  the  necessity  for  irrigation 
depends  on  the  available  amount  of  precipitation,  which  cannot 
be  judged,  however,  from  the  total  annual  precipitation.     Where 
precipitation  is  less  than  20  inches  per  annum,  irrigation  is  generally 
necessary.     This   is  our   "arid  region,"    including   most   of   the 
country  west  of  the  gjth  meridian.     On  the  other  hand,  in  Italy, 
where  the  annual  precipitation  averages  about  40  inches,  irrigation 
is  necessary,  because  most  of  this  occurs  during  the  winter  or  other 
non-agricultural  months.     In  India  the  rainfall  is  in  places  100 
to  300  inches  per  annum,  yet  the  rainfall  during  the  winter  months, 
when  most  of  the  cropping  is  done,  may  be  5  or  10  inches.     The 
cropping  season  in  the  arid  West  may  be  taken  as  occurring 
between  April  and  August,  inclusive,  which  is  the  driest  season  in 
the  year. 

In  referring  to  the  lands  of  the  United  States  in  irrigation 
parlance,  those  of  the  extreme  West  are  called  "arid";  those 
between  the  Mississippi  valley  and  the  Rocky  Mountains  are 
spoken  of  as  " semi-humid";  and  the  lands  to  the  east  thereof  are 
referred  to  as  "humid,"  being  those  on  which  rainfall  suffices  for 
the  production  of  crops.  This  distinction  is  arbitrary,  b-ing  based 
upon  the  mean  annual  precipitation.  The  true  distinction  between 
arid  and  humid  regions  is  dependent  upon  the  precipitation  during 
the  crop-growing  season. 

8.  General  Rainfall  Statistics.— Table  II  shows  the  precipita- 

7 


8 


PRECIPITATION,    RUNOFF,    AND    STREAM-FLOW 


tion  over  the  arid  region.  It  will  be  seen  that  the  average  annual 
rainfall  over  the  northern  portion  of  the  Pacific  Coast  would  be 
sufficient  for  the  production  of  crops,  providing  it  fell  during  the 
irrigating  season.  There  is  also  a  small  area  on  the  headwaters 
of  Gila  and  Salt  rivers  in  Arizona,  where  the  annual  rainfall  is 
apparently  sufficient  for  the  maturing  of  crops.  The  amount  of 
precipitation  is  greatly  influenced  by  altitude.  Thus  in  the  same 
latitude  between  Reno,  Nevada,  and  San  Francisco,  California, 
the  average  annual  precipitation  in  the  bottom  of  the  Sacramento 
valley  is  about  1 5  inches.  To  the  eastward  of  this  the  precipitation 
increases  in  amount  with  the  height  of  the  mountains  until  along 
their  summits  it  averages  from  50  to  60  inches.  Still  farther  east 
it  decreases  with  the  diminishing  altitude  until  in  Nevada  the  mean 
precipitation  is  from  5  to  10  inches.  Precipitation  in  the  high 
mountains  is  much  greater  than  in  adjacent  low  valleys;  hence, 
while  the  rainfall  may  be  insufficient  to  mature  crops  in  the  valleys, 
precipitation  in  the  mountains  may  furnish  abundant  supply  for 
the  perennial  discharge  of  streams  or  for  filling  storage  reservoirs. 
Precipitation  increases  with  altitude  in  the  Sierras  of  California 
at  the  rate  of  0.6  inch  per  100  feet  increase  in  elevation.  The 
increase  of  precipitation  with  altitude  may  be  represented  by  the 
formula  i  -{-  1.92/2-  —  o.^h2  +  o.o2h3,  in  which  h  is  the  number 
of  times  less  one  that  1000  is  contained  in  the  elevation  in  feet. 

In  connection  with  the  study  of  the  increase  of  rainfall  with 
an  increase  in  elevation,  the  following  table  is  of  interest : 


Station. 

Length  of 
Record. 

Elevation 
above 
McDowell. 

Measured 
Rain. 

Constant 
Increase 
per  100 
Feet  Rise. 

^McDowell 

Yr.      Mo. 

2  3              IO 

Feet. 

Inches. 
10   38 

Inches. 
Base 

Lowell 

IQ                ^ 

1  1  ^O 

12    37 

O    17 

Fort  Grant 

17               2 

•2610 

16  85 

18 

Fort  Apache  

x  / 

18         10 

3800 

21    O4 

28 

Verde     

22 

IQIO 

13     13 

j  e 

Prescott  

23              II 

4I4O 

17   06 

16 

p.  Rainfall  Distribution  in  Detail.— In  the  Gila  and  Salt  river 
valleys  in  the  neighborhood  of  Phoenix,  Arizona,  the  average  an- 


GREAT   RAINFALLS  9 

nual  rainfall  is  between  5  and  10  inches,  while  on  the  headwaters 
of  these  streams  it  averages  13  inches.  During  the  summer  or 
irrigating  months,  the  precipitation  is  from  3  to  5  inches  in  the 
neighborhood  of  Phoenix  and  Florence.  In  the  lower  Rio  Grande 
and  Pecos  river  valleys  in  New  Mexico  the  average  annual  pre- 
cipitation is  10  inches.  Over  the  remainder  of  the  agricultural  por- 
tion of  the  Territory  it  averages  about  1 5  inches.  In  winter  the 
precipitation  is  comparatively  low  in  the  valleys,  but  compara- 
tively high  in  the  uplands.  In  the  summer  or  irrigating  months 
it  ranges  between  4  and  8  inches  in  the  Rio  Grande  and  Pecos 
valleys.  In  California  in  the  Sacramento  valley  the  average  an- 
nual precipitation  is  about  15  inches,  and  in  the  San  Joaquin 
valley  from  10  to  15  inches.  Over  the  agricultural  portions  of 
Southern  California  it  averages  about  the  same.  A  large  pro- 
portion of  this  occurs  during  the  early  spring  months.  Over  the 
plains  of  Western  Nevada  the  average  annual  precipitation  is 
between  5  and  10  inches,  most  of  which  occurs  at  periods  other 
than  in  the  irrigating  season.  On  the  plains  of  Utah  the  aver- 
age annual  precipitation  is  from  10  to  15  inches,  while  the  pre- 
cipitation during  the  summer  months  is  but  an  inch  or  two. 

In  the  upper  Missouri  and  Yellowstone  valleys  of  Montana  the 
average  annual  precipitation  is  from  12  to  20  inches,  of  which  about 
5  inches  falls  during  the  irrigating  season.  In  the  Snake  River 
valley  of  Idaho  the  average  annual  precipitation  is  about  10  inches 
of  which  about  3  inches  falls  during  the  irrigating  season.  In  the 
Platte  and  Arkansas  valleys  of  Colorado  the  average  annual  pre- 
cipitation is  about  15  inches,  of  which  from  7  to  10  inches  falls 
during  the  irrigating  season.  In  the  eastern  portion  of  Colorado 
on  the  plains  nearer  the  Kansas  line  the  precipitation  is  a  little  less 
than  this  and  about  the  same  as  in  the  upper  Rio  Grande  valleys. 

10.  Great  Rainfalls. — An  important  consideration  in  designing 
irrigation  works  is  the  maximum  amount  of  rainfall  which  may 
occur.  Great  floods  are  the  immediate  result  either  of  the  sudden 
melting  of  snow  in  the  mountains  or  of  heavy  and  protracted 
rain-storms.  On  most  watersheds  there  are  periods  of  maximum 
rainfall,  the  recurrence  and  effect  of  which  are  worthy  of  note. 
In  the  neighborhood  of  Yuma,  Arizona,  the  average  annual 


10 


PRECIPITATION,    RUNOFF,    AND    STREAM-FLOW 


rainfall  is  about  3  inches,  yet  in  the  last  week  of  February,  1891, 
2\  inches  fell  in  24  hours.  The  average  annual  rainfall  in  the 
neighborhood  of  San  Diego,  California,  is  about  12  inches,  yet 
in  the  storms  of  February,  1891,  13  inches  fell  in  23  hours  and 
inches  in  54  hours.  In  the  neighborhood  of  Bear  valley 

TABLE  II. 

PRECIPITATION   BY    RIVER   BASINS. 


Station. 


Altitude. 
Feet. 


Mean  Annual 

Precipitation. 

Inches. 


Rio  GRANDE: 

Summit,  Colorado 11300 

Fort  Lewis,  Colorado 8500 

Fort  Garland,      "       7937 

Saguache,              "       774° 

Santa  F£,  New  Mexico ; 7026 

Fort  Wingate,  New  Mexico 6822 

Las  Vegas,                        "     6418 

Albuquerque,        "             ;     5°32 

Socorro,                                    4560 

Deming,                             "     4315 

GIL  A  RIVER: 

Fort  Bayard,  New  Mexico 6022 

Prescott,  Arizona 5389 

Fort  Apache,  Arizona 5°5° 

Fort  Grant,           "       4914 

Phcenix,                 "       1068 

Texas  Hill,           "       353 

Yuma,                    "       137 

PLATTE  RIVER: 

Pike's  Peak,  Colorado 14134 

Fort  Saunders,  Wyoming 7180 

Fort  Fred  Steele      "     6850 

Cheyenne,                  "      6105 

Colorado  Springs,  Colorado 6010 

Denver,                                    5241 

Fort  Morgan,               "         .  . .  . 4500 

MISSOURI  RIVER: 

Virginia,  Montana 5480 

Fort  Ellis,       "       4754 

Helena,            "       4266 

Fort  Shaw,     "       2550 

Poplar,            "       1955 


29  .00 

17.19 

12.74 

42  .60 

14-25 

14.71 

22.08 

7.19 

8.01 

8-95 

14  .06 

17  .06 

19.54 

15-34 

7-35 

3-47 

3.00 

28.65 

12  .92 
11.03 
11.32 
14.79 
14.40 
8.08 

1 6. oo 
19  .60 
13.18 

10  .22 

10  .50 


reservoir  east  of  Redlands,  California,  during  the  same  storm,  17 
inches  of  rain  fell  in  24  hours.  Perhaps  the  greatest  rainfall 
recorded  for  24  hours  was  that  of  31.72  inches  at  Nedunkeni, 
Ceylon.  Such  storms  as  these  may  be  very  destructive  both  to 
crops  and  works.  The  average  annual  discharge  of  Salt  River 


SUDDENNESS    OF    GREAT    STORMS  II 

in  Arizona  is  about  1000  second-feet,  and  the  average  flood  dis- 
charge is  perhaps  10,000  second-feet;  yet,  as  the  result  of  a 
sudden  rain-storm  of  unusual  violence  which  occurred  in  the 
spring  of  1890,  this  river  increased  to  a  flood  discharge  of  140,000 
second-feet,  and  in  the  spring  of  1891,  as  the  result  of  a  still 
greater  cloud-burst,  its  discharge  reached  the  enormous  figure  of 
nearly  300,000  second-feet. 

11.  Suddenness    of    Great    Storms. — Statistics    showing    the 
rainfall  in  24  hours  furnish  insufficient  data  on  which  to  estimate 
the   suddenness    of    floods    resulting    from    great    storms.     In 
Baltimore,  Md.,  on  July  12,  1903,  there  fell  14.45  inches  of  rain 
in  2  hrs.  20  min.     In  Atlantic  City  5.45  inches  fell  in  4  hrs.  30 
min.  on  July  22,  1903.     The  greatest  and  most  prolonged  storm 
on  record  is   probably  that  which  occurred  on   the  line  of  the 
Lower  Ganges  canal  in  the  Northwest  Provinces  of  India.     On 
the  i3th  of  September,  1884,  16  inches  fell;    on  October  the  ist, 
22  inches;    on   the   2d,  22^   inches;  on  the  3d,  18  inches;  and 
on  the  4th,  iyj  inches  of  rain  fell.     In  some  cases  and  at  some 
times  the  precipitation   was  as  high  as  5  inches  per  hour.     In 
the  Baltimore  storm  just  quoted  the  rate  per  hour  of  precipita- 
tion for  over  two  hours  exceeded  6  inches.     The  maximum  rate 
for  5  minutes  was  9.6  inches  per  hour.     Such  storms  as  these 
do  far  greater  damage  than  protracted  storms  of  less  violence. 

12.  Precipitation   on   River    Basins. — Table   II,    giving    the 
rainfall  in  a  few  of  the  principal  river  basins  of  the  West,  shows 
very  clearly  the  variation  in  the  amount  of  precipitation  at  different 
altitudes,  corrected  to  1901. 

13.  Rainfall  Statistics  by  States.— Table  III  gives  the  average 
annual  precipitation,  and  the  precipitation  during  the  irrigating 
season,  from  April  to  August  inclusive,  for  various  places  in  each 
of  the  Western  States,  corrected  to  1900. 

14.  Gauging  Rainfall. — The  common   rain-gauge  or   pluvi- 
ometer for  the  measurement  of  precipitation  is  illustrated  in  Fig. 
i.     It  consists  of  three  parts,  the  collector  A1  the  receiver  B,  and 
the   overflow    attachment    C.     A    measuring-rod    graduated    to 
inches  and  tenths  is  used  in  measuring  the  depth  of  water.     This 
gauge  should  be  placed  in  an  open  space,  preferably  over  grass 


12 


PRECIPITATION,    RUNOFF,    AND    STREAM-FLOW 


TABLE  III. 

PRECIPITATION    BY    STATES. 


Locality. 

Altitude. 
Feet. 

Mean 
Annual  Pre- 
cipitation. 
Inches. 

Mean  Pre- 
cipitation, 
April  to 
August. 
Inches. 

ARIZONA  : 
Fort  Apache  

sOSO 

in    r4 

IO    27 

Holbrook  

CO47 

0    2Q 

3  68 

Casa  Grande 

1308 

53  7 

Phoenix 

1068 

•oo 
71  c 

*  •  o* 

2    27 

Texas  Hill  

sec 

•2.47 

,66 

Prescott                            

rsgn 

1  7  06 

7O4 

Flagstaff                   

6886 

20  40 

Yuma                

1  37 

300 

I    06 

NEW  MEXICO: 
Springer             

^766 

ii  82 

8  86 

Las  Vegas     

6418 

22    08 

12     7O 

Albuquerque  

1^026 

7    10 

422 

Santa  Fe  

$v*v 

7026 

14    2Z 

8  32 

Fort  Wingate  

6822 

14  .71 

o  -6* 

6  07 

Socorro  

4^6? 

IO  .31 

s»* 

3.87 

Deming  

4-227 

8.CK 

3  .00 

CALIFORNIA  : 
Yreka  

2631; 

16  .34 

3  .33 

Fort  Bid  well 

:f«W 

4640 

2O   84 

4^4 

Redding 

ss6 

34    60 

*  61 

Oroville 

1  88 

2C    IA 

3    48 

Bowman  L)am 

^400 

71    22 

Summit 

7OI7 

43    ^6 

Placerville 

21  IO 

AC    17 

8  26 

Sacramento 

64 

to  •*/ 
2O    87 

2    73 

San  Jose 

O4 

14    ^2 

*  -/o 
2  .08 

Amerced 

171 

IO    3O 

73 

Fresno 

A  /  A 
328 

0  «O2 

•/«5 

.80 

Visalia 

O'" 

348 

8  .84 

.86 

San  Bernardino 

QsO 

17  .16 

•  37 

Banning              

2317 

14  .30 

.80 

Los  Angeles                   

3  -2O 

17  .31 

.81 

San  Diego          

02 

IO  .?! 

2  -47 

Independence  

3721 

c  .72 

NEVADA  : 
Reno  

4407 

5  -1? 

o  .71 

\Vinnemucca 

4?c8 

8  08 

2  .70 

Palisade 

4840 

'7w 
8  .42 

2.17 

Fort  Churchill                       .    . 

4284 

C  .7,1 

I  .70 

Carson                                

4628 

II  .07 

2  .O? 

Pioche                       

6110 

II  .10 

4  -41 

COLORADO: 
Greeley                 

47sO 

13  .41 

o  .16 

0^24 

28.21; 

Leadville          

IO2OO 

II  .56 

Pike's  Peak             

14134 

28.65 

Canyon  City              

47OO 

II  .^2 

7  .01 

GAUGING   RAINFALL 
TABLE  III. — Continued. 


Locality. 

Altitude. 
Feet. 

Mean 
Annual  Pre- 
cipitation. 
Inches. 

Mean  Pre- 
cipitation, 
April  to 
August. 
Inches. 

COLORADO  —  Continued: 
Pueblo 

475  3 

12    II 

7    TO 

Fort  Lyon 

iQOO 

1  1   O7 

8  15 

Monte  Vista, 

776? 

6   QI 

"  «*3 

4    l8 

Trinidad 

6O7O 

21    6l 

I  5    06 

Denver 

C.24I 

14   4O 

900 

Grand  Junction           

457Q 

8    en 

WASHINGTON  : 
Spokane                              .                 . 

I800 

l8   25 

Walla  Walla                      

O2  3 

10.^ 

IO    77 

UTAH: 
Ocden 

47.40 

I  3    46 

4    12 

Salt  Lake                   

43C.4 

M-4" 
IO    10 

6  26 

Nephi                      

5  5  S^ 

"  **v 

18  10 

7    4O 

St   George             

xo  .iy 
6   74 

I    7.2 

IDAHO: 
Eagle  Rock              

4781 

18  67 

4   60 

Boise                     

1108 

14  .42 

41  » 

Lewiston            

64.7 

18  25 

c    cr 

Fort  Hall             

17    51 

5  Oi 

O  djt 

Pocatello  

4471 

It    27 

WYOMING  : 
Cheyenne            

6105 

12  .20 

C      Cf 

Fort  McKinney   

9.OO 

4    4C. 

Lander            

C3.77 

12  .20 

MONTANA  : 
Fort  Benton   

277O 

17  .7Q 

c    4C 

Miles  City        

4.770 

12  ,7O 

C      CC 

Helena   

4266 

n  .18 

j  O3 
4  48 

Fort  Shaw  

25C.O 

IO  .22 

4    25 

OREGON: 
Baker  

2.441 

jc  .if 

Roseburg  

•*.» 

482 

5       *      , 

7C  .JO 

TEXAS: 
El  Paso  

3,710 

9.77, 

Amarillo 

3.6l  5 

1  8     2O 

sod,  and,  to  obtain  a  free  exposure  to  the  rain,  should  be  at  least 
30  feet  from  any  building  or  obstruction.  It  should  be  enclosed 
in  a  close-fitting  box  and  sunk  into  the  ground  to  such  a  depth 
that  the  upper  rim  of  the  gauge  shall  be  about  one  foot  above 
the  surface,  and  care  should  be  taken  to  maintain  it  in  a  horizontal 
position.  The  sectional  area  of  the  receiver  being  only  .1  of  the 
area  of  the  collector,  the  depth  of  water  measured  is  ten  times 
the  true  rainfall. 


PRECIPITATION,    RUNOFF,    AND    STREAM-FLOW 


FIG.    i. — Rain-gauge. 


In  the  measurement  of  snowfall  the  funnel  and  receiver 
should  be  removed  and  only  the  overflow  attachment  used  as 
the  collecting  vessel.  It  should  be  set  as  in  the  case  of  rainfall, 

and  the  snow  should  be  melted  after 
being  collected.  Where  the  wind 
is  blowing  hard  it  is  advisable  to 
measure  the  snow  in  a  different 
manner.  After  the  snow  has  ceased 
to  fall  a  spot  should  be  selected 
where  it  has  an  average  depth.  The 
overflow  attachment  is  inverted  and 
lowered  until  the  rim  has  reached 
the  full  depth  of  the  newly  fallen 
snow,  when  a  piece  of  flat  tin  or 
other  material  is  slipped  under  the 
rim  and  the  gauge  lifted  and  the  snow  melted  as  before. 

15.  Runoff. — By  " runoff"   is  meant  the  quantity  of  water 
which  flows  in  a  given  time  from  the  catchment  basin  of  a  stream. 
It  includes  not  only  that  portion  of  the  rainfall  which  flows  over 
the  surface  during  storms,  but  also  water  which  is  derived  from 
subsurface  sources,  as  springs,  etc.     The  runoff  of  a  given  catch- 
ment area  may  be  expressed  either  as  the  number  of  second-feet 
of  water  flowing  in  the  stream  draining  that  area,  or  as  the  number 
of  inches  in  depth  of  a  sheet  of  water  spread  over  the  entire  catch- 
ment.    The  latter  expression  indicates  directly  a  percentage  of 
rainfall  in  inches  which  runs  off.     Finally,  runoff  may  be  ex- 
pressed volu metrically  as  so  many  cubic  feet  or  acre-feet. 

1 6.  Variability  of  Runoff. — As  runoff  bears  a  direct  relation 
to  precipitation,  it  appears  that,  knowing  the  amount  of  rainfall 
and  the  area  of  the  catchment  basin,  the  amount  of  runoff  can 
be  directly  ascertained.     This  is  not  the  case,  however,  as  the 
amount  of  runoff  is  affected  by  varying  climatic  and  topographic 
factors.     Many  formulas,  none  of  which  give  satisfactory  results, 
have  been  worked  out  for  obtaining  the  relation  between  runoff 
and  precipitation.     If  the  climate  be  the  same  over  two  given 
catchment  basins,  the  runoff  will  be  affected  by  the  depth  of  the 
soil,  the  amount  of  vegetation,  the  steepness  of  the  slopes,  the 


RUNOFF  15 

geologic  structure,  and  the  amount  of  snow  on  the  ground  when 
followed  by  rainfall  or  warm  weather. 

The  climatic  influences  bearing  most  directly  on  runoff  are 
the  total  amount  of  precipitation,  its  rate  of  fall,  and  the  tempera- 
ture of  air  and  earth.  Thus,  where  most  of  the  .precipitation 
occurs  in  a  few  violent  showers  the  percentage  of  runoff  is  higher 
than  where  it  is  given  abundant  time  to  enter  the  soil.  If  the 
temperature  is  high  and  the  wind  strong,  much  greater  loss  will 
occur  from  evaporation  than  if  the  ground  is  frozen  and  there 
is  no  air  movement.  Within  a  given  drainage  basin  the  rates 
of  runoff  vary  on  its  different  portions.  Thus  in  a  large  basin 


DEPTH  OF  MEAN  ANNUAL  RAINFALL  IN  INCHES. 

S         9         8         8          8          8 


FIG.  2. — Relation  of  Runoff  to  Rainfall. 

the  rate  of  runoff  for  the  entire  area  may  be  low  if  the  greater 
portion  of  the  basin  is  nearly  level,  but  at  the  headwaters  of  the 
streams  where  the  slopes  are  steep  and  perhaps  rocky  the  rate 
of  runoff  will  be  higher.  The  coefficient  of  runoff  increases  with 
the  rainfall.  Thus  in  humid  regions  where  the  rainfall  is  greatest 
the  rate  of  runoff  is  highest. 

17.  Relations  of  Rainfall  to  Runoff. — The  above  diagram 
(Fig.  2),  by  Mr.  F.  H.  Newell,  gives  graphically  an  excellent 
means  of  obtaining  the  average  runoff  due  to  the  average  precipi- 


1 6  PRECIPITATION,    RUNOFF,    AND    STREAM-FLOW 

tation.     The  relation  between  these  changes  with  various  con- 
ditions, and  is  chiefly  influenced  by  the  topography. 

The  heights  above  the  base  represent  depths  in  inches  of 
the  mean  annual  runoff,  and  the  distance  from  left  to  right  the 
depths  of  rainfall  upon  the  surface  of  the  drainage  basin.  The 
diagonal  line  represents  the  limit  when  all  of  the  rain,  falling  as 
upon  a  smooth,  steeply  sloping  roof,  runs  off;  the  horizontal  base 
represents  the  limit  where  none  of  the  water  flows  away.  Be- 
tween these,  the  lower  of  the  two  curved  lines  represents  the  con- 
ditions prevailing  in  a  catchment  basin  of  broad  valleys  and 
gentle  slopes,  from  which  the  amount  of  runoff  is  relatively 
small ;  and  the  upper  curve  an  average  condition  in  mountainous 
regions,  from  which  the  amount  of  runoff  is  relatively  large. 
For  example,  with  a  rainfall  of  35  inches  on  a  mountainous  catch- 
ment basin  the  runoff  is  about  23  inches,  while  for  a  rainfall  of 
35  inches  on  a  slightly  inclined  or  undulating  catchment  basin 
the  runoff  amounts  to  about  1 1  inches. 

1 8.  Formulas  for  Maximum  Runoff. — The  maximum  dis- 
charge from  the  catchment  basin  tributary  to  a  reservoir  is  a  factor 
of  great  importance  in  designing  its  dam  or  wasteway.  Several 
formulas  for  ascertaining  the  maximum  discharge  from  a  given 
catchment  basin  have  been  obtained  both  empirically  from 
known  measurements  and  by  theoretic  processes.  Mr.  J.  T. 
Fanning  found  by  plotting  a  curve  derived  from  the  flood  dis- 
charges of  some  American  streams  that  the  resulting  equation 
for  flood  flow  became 

D  =  200  (M )«, (i) 

in  which  M  is  the  area  of  catchment  in  square  miles,  and  D  the 
volume  of  discharge  of  the  whole  area  in  second-feet. 

In  India  Colonel  Ryves  derived  the  following  formula  for 
runoff, 

D  =  C{/W, (2) 

and  Colonel  Dickens  the  formula 

D  =  CV~M*  .     .    ,.  -.,,>.  v.--     (3) 

No  such  formulas  can  be  strictly  applied  with  the  same  co- 
efficient to  areas  of  varying  size,  and  all  must  be  used  with  dis- 


FLOOD    DISCHARGES    OF    STREAMS  17 

cretion,  as  their  results  are  greatly  influenced  by  different  con- 
ditions from  those  under  which  they  were  obtained.  In  regions 
where  maximum  recorded  rainfalls  of  from  3  to  6  inches  in  24 
hours  have  occurred  the  following  values  of  C  have  been  deter- 
mined for  Dickens's  formula: 

Rainfall  3.5  to  4  inches  in  flat  country,  C  =  2oo;  mixed 
country,  C  =  2$o;  hilly  country,  C  =  3Oo;  and  for  a  maximum 
rainfall  of  6  inches,  C  varies  between  300  and  350.  For  Ryves' 
formula  the  coefficient  varies  between  400  and  500  in  flat  country, 
and  for  hilly  areas  where  the  maximum  rainfall  is  high  it  may 
reach  650.  The  shape  of  the  catchment  basin  is  an  important 
factor  in  the  formula  of  maximum  discharge. 

19.  Flood  Discharges  of  Streams. — It  is  desirable  to  know 
the  monthly  and  daily  rates  of  runoff  as  well  as  the  mean  annual 
runoff  of  a  catchment  basin,  in  order  that  dams  and  weirs  may 
be  designed  with  ample  wasteways.     The  greatest  floods  occur 
either  on  barren  catchment  basins  having  steep  slopes  or  where 
heavy  snowfalls  are  followed  by  warm,  melting  rains.     On  the 
Gila  and  Salt  river  basins  in  Arizona  the  percentages  of  runoff 
.are  exceptionally  high  during  occasional  severe  storms.     The 
highest  recorded  flood  on  the  Salt  River  above  Phoenix  occurred 
in  February,  1891,  and   amounted  to  about  300,000  second-feet 
from  a  catchment  basin  of  12,260  square  miles.     This  is  equiva- 
lent to  nearly  30  second-feet  per  square  mile  of  catchment  area, 
while  the  stream  a  few  days  prior  to  the  occurrence  of  the  storm 
was  not  discharging  over  1000  second-feet,  or  one-twelfth  of  a 
second-foot  per  square  mile.     Sudden  great  storms  (Article  n) 
may  in  the  West  cause  maximum  flood  discharges  as  great  as 
300  second-feet  per  square  mile  of  catchment  area  for  short  periods 
of  time.     Observations  by  Mr.  Desmond  Fitzgerald  at  the  Boston 
Water  Works  indicate  that  the  greatest  freshets  observed  there 
caused  a  discharge  during  24  hours  at  the  rate  of  150  second-feet 
per   square   mile.     Wasteways   for   dams   should    be   designed 
accordingly. 

20.  Amounts  of  Stream  Discharge  and  Runoff. — Table  IV, 
derived   from  observations  extending    over    a    series   of    years 
to  1900,  shows  the  discharge  and  amounts  of  runoff  from  the 


18  PRECIPITATION,    RUNOFF,    AND    STREAM-FLOW 


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2O  PRECIPITATION,    RUNOFF,    AND    STREAM- FLOW 

catchment  basins  of  the  more  important  streams  of  the  arid 
region. 

A  study  of  this  table  will  show  that  the  average  daily  amount 
of  water  which  may  be  furnished  by  a  catchment  basin  for  storage 
varies  between  o.i  and  3.5  acre-feet  per  square  mile  of  catchment 
area.  These  figures  correspond  rather  closely  with  those  obtained 
at  the  Boston  Water  Works  and  at  San  Francisco  for  approxi- 
mately corresponding  amounts  of  rainfall. 

The  runoff  may  be  well  expressed  in  percentages  of  the  depth 
of  precipitation.  Thus  in  the  drainage  basin  of  the  Potomac 
River  the  average  annual  precipitation  is  45.47  inches,  and  the 
average  runoff  24.03  inches  in  depth,  which  may  be  expressed  as 
52.7  per  cent  of  the  precipitation.  In  years  of  minimum  pre- 
cipitation the  per  cent  of  runoff  on  this  basin  is  39.2;  from  May 
to  December  it  averages  73.7,  and  from  June  to  November 
33  per  cent.  Similar  percentages  obtain  in  the  other  eastern 
catchment  basjns.  In  arid  regions  and  in  dry  seasons  the  per- 
centage of  runoff  is  much  smaller  for  similar  slopes,  topography, 
and  soil  cover  than  in  humid  regions  or  in  wet  seasons. 

21.  Discharge  in  Seasons  of  Minimum  Rainfall. — Where  the 
number  of  storage  basins  is  limited  it  becomes  desirable  to  save 
all  the  water  possible  and  frequently  to  impound  enough  to  carry 
over  a  period  of  two  or  three  years  of  minimum  rainfall.     In 
general  it  has  been  found  that  cycles  of  mean  low  rainfall  occur 
every  two  or  three  years  when  the  amount  of  precipitation  is  less 
than  0.8  of  the  mean.     The  least  of  these  three-year  low  cycles 
has  been  found  to  average  as  low  as  0.7  of  the  mean  annual  rain 
fall. 

22.  Regimen  of  Western  Rivers. — Eastern  rivers  usually  drain 
comparatively  level  catchment  basins,  well  covered  with  timber 
and  grass.     Hence  the  soil  is  deep  and  the  rate  of  runoff  con- 
sequently low  and  the  streams  comparatively  constant  in  their 
discharge,  being  subject  to  few  and  not  excessive  flood  rises. 
This  because  the  larger  portion  of  the  water  reaches  these  streams 
by  seepage.     In  the  arid  West  the  regimen  of  the  streams  is  the 
reverse  of  this.     The  catchment  basins  are  precipitous  and  barren. 
Little  water  soaks  into  the  soil  to  supply  the  streams  from  springs. 


MEAN    DISCHARGE    OF    STREAMS  21 

After  a  heavy  storm  most  of  the  water  runs  off  in  a  very  short 
period  of  time,  resulting  in  great  floods.  Thus  streams  which 
at  flood  height  may  reach  from  10,000  to  15,000  second-feet 
discharge  for  a  few  hours  or  days  may  sink  within  a  week  or  so 
to  paltry  rills  of  a  few  second-feet  discharge  or  may  entirely  dis- 
appear. With  such  streams  it  becomes  necessary  to  design  works 
in  such  manner  that  most  of  the  discharge  may  be  saved  by  stor- 
age within  a  short  period  of  time. 

23.  Mean   Discharge    of    Streams. — When    definite   data    of 
the  annual  discharge  of  a  stream  are  not  available  they  may  be 
obtained  approximately  by  multiplying  the  depth  of  runoff  in 
inches  by  the  area  in  square  miles  of  its  catchment  basin.     As 
shown  in  Article  17,  the  proportion  of  rainfall  which  runs  off 
varies  between  30  and  80  per  cent,  according  as  the  slopes  are 
flat  or  steep,  wooded  or  barren.     The  mean  discharge  ranges 
between  0.5  and  2.0  second-feet  per  square  mile  of  catchment  area. 

24.  Available  Annual  Flow  of  Streams. — Where  irrigation  is 
practised  all  of  the  water  flowing  in  the  streams  is  not  available 
for  storage,  since  much  of  it  is  already  appropriated  by  irrigators, 
and   this   quantity   must  be  deducted  from  that  available  for 
storage.     A  large  portion  of  the  discharge  occurs  in  winter  when 
the  streams  are  covered  with  ice  which  renders  it  practically 
impossible  to  divert  the  water  for  storage,  though  it  is  available 
for  such  reservoirs  as  may  be  on  the  main  streams.     As  nearly 
all  of  the  flow  occurring  in  the  irrigating  season  is  appropriated, 
only  the  surplus  and  flood  water  is  available  for  storage. 

25.  Works  of  Reference.     Precipitation,  Runoff,  and  Stream- 
flow. 


CRAIG,  JAMES.  Discharge  from  Catchment  Areas.  Trans.  Inst.  C.  E.,  vol.  80. 
London,  1884. 

FANNING,  J.  T.  A  Treatise  on  Hydraulic  and  Water-supply  Engineering.  D. 
Van  Nostrand  Co.,  New  York,  1890. 

FITZGERALD,  DESMOND.  Maximum  Rates  of  Rainfall.  Trans.  Am.  Soc.  C.  E., 
vol.  21.  New  York,  1889. 

-  Rainfall,  Flow  of  Streams,  and  Storage.     Trans.  Am.  Soc.  C.  E.,  vol  27. 
New  York,  1892. 

GREELY,  Gen.  A.  W.,  and  GLASSFORD,  Lieut.  W.  A.  Irrigation  and  Water  Stor- 
age in  Arid  Regions.  5ist  Congress,  House  of  Representatives  Executive 
Doc.  No.  287.  Government  Printing  Office,  Washington.  D.  C.;  1801. 


22  PRECIPITATION,    RUNOFF,    AND    STREAM-FLOW 

GREELY,  Gen.  A.  W.  Report  of  Rainfall.  5oth  Congress,  Senate  Executive  Doc. 
No.  91.  Government  Printing  Office,  Washington,  D.  C.,  1888. 

NEWELL,  F.  H.  Parts  II  of  nth  to  i4th  Annual  Reports,  U.  S.  Geological  Sur- 
vey. Government  Printing  Office,  Washington,  D.  C.,  1890  to  1893. 

• Hydrography.  Bulletin  131,  U.  S.  Geological  Survey.  Government 

Printing  Office,  Washington,  D.  C.,  1895. 

• Agriculture  by  Irrigation.  Report  of  Eleventh  Census,  1890.  Govern- 
ment Printing  Office,  Washington,  D.  C.,  1894. 

UNITED  STATES,  Census  of  Agriculture.  Eleventh  Census,  1890,  and  Twelfth 
Census,  1900.  Government  Printing  Office,  Washington,  D.  C. 

• Geological  Survey,  Numerous  Annual  Reports  and  Water-supply  Papers 

since  1890.  Government  Printing  Office,  Washington,  D.  C. 

Reclamation  Service,  Annual  Reports  since  1902.  Government  Printing 

Office,  Washington,  D.  C. 


CHAPTER  III 

EVAPORATION,    ABSORPTION,    AND   SEEPAGE 

26.  Evaporation    Phenomena. — The    rapidity    with    which 
water,  snow,  and  ice  are  converted  into  vapor  is  dependent  upon 
the  relative  temperatures  of  the  water  and  atmosphere  and  upon 
the  amount  of  motion  in  the  latter.     Evaporation  is  greatest 
when  the  atmosphere  is  dryest,  when  the  water  is  warm  and 
a  brisk  wind  is  blowing.     It  is  least  when  the  atmosphere  is 
moist,  the  air  quiet,  and  the  temperature  of  the  water  low.     In 
summer  the  cool  surfaces  of  deep  waters  condense   moisture 
from  the  warm  air  passing  across  them  and  thus  gain  in  moisture 
when  they  are  supposed  to  be  evaporating.     When  the  reverse 
conditions  exist  in  the  atmosphere  and  the  winds  are  blowing 
briskly  across  the  water  the  resultant   wave- motion   increases 
the  agitation  of  the  body  and  permits  its  vapors  to  escape  freely 
into  the  large  volumes  of  unsaturated  air  which  are  rapidly  pre- 
sented in  succession  to  attract  its  vapors.     Evaporation  is  con- 
stantly taking  place  at  a  rate  due  to  the  temperature  of  the  surface, 
and  condensation  is  likewise  going  on  from  the  vapors  existing 
in  the  atmosphere,  the  difference  between  the  two  being  the 
rate  of  evaporation. 

From  the  above  it  will  be  seen  that  evaporation  should  be 
greatest  in  amount  in  the  desert  regions  of  the  Southwest  and 
least  in  the  high  mountains.  Tables  V  and  VI  show  this  to 
be  the  case,  and  that  in  the  same  latitude  evaporation  differs 
greatly  in  amount  according  to  the  altitude. 

27.  Measurement  of  Evaporation. — Two  or  three  methods 
have  been  devised  for  measuring  evaporation,  none  of  which  are 
wholly   satisfactory.     Elaborate  and   expensive   apparatus   has 
been  employed  in  evaporation  measurements  made  by  Mr.  Des- 
mond Fitzgerald,  chief  engineer  of  the  Boston  Water  Works; 
by  Mr.   Charles  Greaves  of   England,  and  others.     A  simple 

23 


24      EVAPORATION,  ABSORPTION,  AND  SEEPAGE 

apparatus  and  one  quite  as  successful  as  the  more  elaborate 
contrivances  is  that  employed  by  the  U.  S.  Geological  Survey. 
It  consists  of  a  pan,  Fig.  3,  so  placed  that  the  contained  water 
has  as  nearly  as  possible  the  same  temperature  and  exposure 
as  that  of  the  body  of  water  the  evaporation  from  which  is  to  be 


FIG.  3. — Evaporating-pan. 

measured.  This  evaporating-pan  is  of  galvanized  iron  3  feet 
square  and  18  inches  deep,  and  is  immersed  in  water  and  kept 
from  sinking  by  means  of  floats  of  wood  or  hollow  metal.  It 
should  be  placed  in  the  water  in  such  position  as  to  be  exposed 
as  nearly  as  possible  to  its  average  wind  movements.  The  pan 
must  be  rilled  to  within  3  or  4  inches  of  the  top  that  the  waves 
produced  by  the  wind  shall  not  cause  the  water  to  slop  over,  and 
it  should  float  with  its  rim  several  inches  above  the  surrounding 


AMOUNT   OF   EVAPORATION  25 

surface,  so  that  waves  from  this  shall  not  enter  the  pan.  The 
device  for  measuring  the  evaporation  consists  of  a  small  brass 
scale  hung  in  the  centre  of  the  pan.  The  graduations  are  on  a 
series  of  inclined  crossbars  so  proportioned  that  the  vertical 
heights  are  greatly  exaggerated,  thus  permitting  a  small  rise  or 
fall,  say  of  a  tenth  of  an  inch,  to  cause  the  water  surface  to  ad- 
vance or  retreat  on  the  scale  .3  of  an  inch.  By  this  device,  multi- 
plying the  vertical  scale  by  three,  it  is  possible  to  read  to  .01  of 
an  inch. 

In  1888  a  series  of  observations  were  made  with  the  Piche 
evaporometer  by  Mr.  T.  Russell  of  the  U.  S.  Signal  Sen-ice  to 
ascertain  the  amount  of  evaporation  in  the  West.  •  While  it  is 
probable  that  results  obtained  with  this  instrument  are  not  par- 
ticularly accurate,  comparisons  of  these  results  with  those  ob- 
tained by  other  methods  in  similar  localities  show  such  slight 
discrepancies  that  they  may  be  considered  of  value  until  super- 
seded by  results  obtained  by  better  methods.  Observations 
were  made  with  this  instrument  in  wind  velocities  varying  from 
10  to  30  miles  per  hour,  from  which  it  was  discovered  that  with 
a  velocity  of  5  miles  an  hour  the  evaporation  was  2.2  times  that 
from  one  in  quiet  air;  10  miles  per  hour,  3.8  times;  15  miles, 
4.9  times;  20  miles,  5.7  times;  25  miles,  6.1;  and  30  miles,  6.3 
times. 

28.  Amount  of  Evaporation. — In  Table  V  is  given  the  amount 
of  evaporation  by  months  in  the  year  1888  in  various  sections 
of  the  West  as  derived  from  experiments  with  the  Piche  apparatus. 

As  in  the  case  of  precipitation,  evaporation  decreases  with 
the  altitude  because  of  the  diminished  temperature  in  high  moun- 
tains. Experiments  were  made  to  determine  the  amount  of 
evaporation  in  different  portions  of  the  West  by  the  hydrog- 
raphers  of  the  U.  S.  Geological  Survey.  These  were  made  with 
the  evaporating-pan,  and  the  results  are  probably  (see  Table  VI), 
more  reliable  than  those  obtained  with  the  Piche  instrument. 
These  experiments  were  unfortunately  conducted  for  a  relatively 
short  space  of  time. 

29.  Evaporation  from  Snow  and  Ice. — From  some  experi- 
ments conducted  at  the  Boston  Water  Works  the  amount  of 


26 


EVAPORATION,  ABSORPTION,  AND  SEEPAGE 


evaporation  frcm  snow  and  ice  was  found  to  be  greater  than  is 
generally  believed.  From  snow  it  amounted  to  about  .02  of 
an  inch  per  day,  or  nearly  2  J  inches  in  an  ordinary  season.  From 

TABLE  V. 

DEPTH   OF   EVAPORATION,   IN  INCHES    PER   MONTH   IN    1887-88. 


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3-0 

2.6 

5-2 

1.4 
4-4 
3-0 

.8 
•9 
.8 
.8 
.6 

.6 

•  7 
.  i 

.  2 

3 

.  2 
.2 

.0 
.8 

.8 
•  3 
•9 

1 

1.2 

1.5 
1.4 

1:1 
11 

3.3 

3-7 

1:1 

2.4 
1.9 

rt 
.2 

•  3 

.1 
.  i 
.8 

.0 

.8 

:  -5 

'.8 

3-2 

a 

3-1 

5-4 

2.7 
8.2 

5-4 

6.7 
7-6 

2.1 

rt 

4.1 
6.8 
3-2 
4-3 
4-9 

5-2 

3-9 

5-6 
5-8 
1.8 

C 
i—  > 

3 

H-  ) 

6.8 
9-6 
6.8 

7-2 

6.0 
8.0 
6.0 

6.7 
8-3 
3-0 

3 

1:1 

4.6 

7-7 
4.8 

1:1 

7.2 
8.5 
4-0 

CO 

1 

o 

2.5 

2-9 

2  .0 

3-o 

1-7 
6.1 

2-3 

4-2 
4-2 
2.8 

3-4 

4-2 

1 

.1 

•  5 
.1 
.1 
.7 
•5 
.  i 

•9 
.1 

.0 

.8 
.1 

.  2 

.0 

•  7 
•  9 
.8 

•9 
.7 
.6 
.6 

.2 

.6 
.8 

•  3 
.8 
•  3 

.0 

.7 

.8 
•  4 
-4 

•9 
.  i 

•4 
.6 

3-6 

2.4 

2.2 
3-0 

3-7 

NORTHERN  SLOPE: 
Fort  Assiniboine  
Fort  Custer  
Fort  Maginnis  

4.2 

4.9 

4.6 
5-5 
5-7 
10.4 
6.9 

4-3 
10.5 
1.9 

4.8 
6.1 
3-8 
6.4 
4-4 
8.6 
3.7 

6.8 
6.1 
3-0 

3-5 

1:1 

4-3 

2~.S 

4.6 
4-9 
2-3 

39-5 
52.0 
35-8 
53-4 
35-4 
76.5 
41-3 

59-4 
69  .0 
26.8 
47-2 
54-6 
55-4 

46.1 
54-4 
96.4 
76.0 

82.0 
79-8 
65-5 

101  .2 
56.0 

95-7 
100.6 

48.9 
83.9 
74-4 
68.3 
56.1 

63.9 
42.8 

57-7 

21.  I 

26.8 

18.1 
39-2 

84.8 
54-3 

65-8 
37.2 
37-5 

Helena 

Poplar  River     

Cheyenne  
North  Platte     

MIDDLE  SLOPE: 
Colorado  Springs  

Pike's  Peak 

Dodge  City  
Fort  Elliott  
SOUTHERN  SLOPE: 
Fort  Sill 

4-1 
5-1 

5-4 

7-4 

8.2 

6^2 

5-5 
5-4 

5-2 

4-7 

5-7 
3-9 

3-9 

3-4 
3-0 

4.8 

2.8 

1:1 

.8 
.8 

.7 
•  7 
•  5 

•  5 
.7 
•9 

.  i 

.  2 
.  I 

.6 

.6 
.  i 

.8 

.0 

•  7 

5-2 

6.0 
4.2 
3-6 
6.4 
3-6 
6.6 
6.3 

1.8 

6.2 

3-6 
3-7 

2-7 

3-8 
2.7 
3.6 

1.8 

1.8 
1.8 

2.7 

5-4 
3-7 

3-o 

2.8 

2-5 

4-2 

8-5 
7-3 

8.4 
6.8 
6.8 
9.2 
5-4 
9-6 
8.7 

4.6 
9.1 
7.2 

6.2 

4.3 

6.1 
4-4 

6.2 

2.1 
2-5 

1-4 
3-9 

6.1 
4-3 

5-6 
3-4 

2.7 

5-0 

II.  0 

9.5 

10.7 
8.8 
9.4 

10.2 
6.2 
9.6 

9-3 

5-2 

9-3 
6.9 
7.0 
4-3 

6.5 
5-4 
7-7 

2.8 

4.1 

1.8 
4.7 

7-0 
4.2 

6.0 
3-0 
3-3 

5-8 

12  .0 
10-9 

13.6 
12.9 

13*8 
8.1 

12.6 

11.9 

4.0 

10.  I 

8.9 
ii  .1 
6.5 

6.6 
4-4 

5-7 

2.3 

ii 

3-5 

6-9 
5-6 

7-o 
3-8 

2.8 

9-5 
ii.  4 
9-4 

9-4 
9.2 
7.1 
12.4 
6.6 

II  .0 
12.8 

8.8 
ii-S 
9.2 

10.2 

7-7 

10.  0 

7-7 
9.9 

1.8 

3-2 

1-4 
5-4 

II  .0 

5-9 

9.1 
3-2 
3-2 

7-5 
9.0 
ii.  6 

7-7 
9-8 
6.7 
10.5 
6.5 

10.2 
13-9 

8.1 

12.0 

10.7 
8.3 
6.8 

9-2 

6.4 
7.9 

2.9 

I  -4 

4-7 

10.7 
5-6 

10.2 

3-5 
3-3 

6.2 

5-9 
3-9 

5-6 
6.6 
5-3 
9.0 
4-7 

8.2 

10.6 

5-o 
9-9 
9-6 
6-9 
5-6 

7.4 
3-8 

1.8 
2.4 
I  -4 
5-0 

10.  I 

6.5 

7-6 
3-1 

2-9 

4-5 

5-2 

4-0 

5-2 

6.7 

5-2 

7-9 

8.8 

4.6 
6.6 
6.5 

5-2 

4.2 

5-2 
2-5 

3-4 
1.8 
i!6 

3-2 

10.5 
7-3 

6.7 
4.1 
4-3 

3-4 
5-7 
3-6 

4.6 
5-7 
4.1 

7-2 

3-6 
5-5 
5-9 

2.4 
3-7 
5-0 
3-4 

5-2 
3-2 

.7 
.8 

•  5 
•  3 
.8 

•  7 

5-9 
3-9 

3-8 
3-0 
3-2 

Fort  Davis  
Fort  Stanton  
SOUTHERN  PLATEAU: 
El  Paso  
Santa  Fe            .... 

Fort  Apache  
Fort  Grant 

Prescott  

Keeler 

MIDDLE  PLATEAU: 
Fort  Bidwell  
Winnemucca  
Salt  Lake  City  

Montrose            

Fort  Bridger  
NORTHERN  PLATEAU: 
Boise  City  
Spokane  Falls  
Walla  Walla  
N.  PACIFIC  COAST: 
Fort  Canby  

Tatoosh  Island 

Roseburg  

MID.  PACIFIC  COAST: 
Red  Bluffs  

Sacramento  
S.  PACIFIC  COAST: 
Fresno  
Los  Angeles  
San  Diego  

ice  it  amounted  to  .06  inch  per  day,  or  about  7  inches  in  an  ordi- 
nary season.  The  evaporation  from  snow  is  greater  than  this  in 
the  arid  regions  of  the  West,  especially  on  barren  mountain-tops 


UNIVERSITY 


EVAPORATION    FROM   EARTH  27 

such  as  those  in  Arizona,  Nevada,  and  Utah,  where  they  are 
exposed  to  the  wind  and  the  bright  sunshine. 

30.  Evaporation  from  Earth. — The  amount  of  evaporation 
from  earth  in  the  West  is  a  doubtful  quantity.  Important  ex- 
periments bearing  on  this  were  made  in  England  between  1844 
and  1875.  From  these  it  appears  that  the  amount  of  evaporation 
from  ordinary  soil  is  about  the  same  as  that  from  wate»,  some- 
times exceeding  it  a  little  and  sometimes  being  a  trifle  less,  though 

TABLE  VI. 

DEPTH    OF   EVAPORATION    PER   MONTH,    IN   INCHES. 


1 

Place. 

Annual. 

c 

rt 

1 

March. 

rs 

£ 

| 

j* 

i 

1 

$ 

> 
o 
2 

i 

1889 
1890 
1889 

1880 
1889 
1889 
1890 
1891 
1892 
1889 
1889 
1889 
1890 
1889 
1889 
1880 
1890 
1891 

1890 
1891 
1890 
1904 
1890 
1890 
1890 
1890 
1890 
1890 

Bozeman    Mont        .... 

3  •  4 

4.5 

5  «3 

i   9 

2    6 

Great  Falls   " 

2     7 

6  8 

7  -I 

6.1 

f  Fort  Douglas,  near  1 
Salt    Lake   City,   [  • 
1       Utah  .  j  ; 

Nephi  and  Provo 

10  .  5 

5-7 

g 

3  -7 

4.1 

5  *  l 

7    6 

6.5 

4.6 

.  i 

I  .  2 

.JO  .0 

I  .O 

i.S 

2.1 

3-2 
2-3 

4-8 
4.1 

5-2 

5-3 

i:! 

7.6 
6.5 
5-0 
7-9 

6-5 
7-3 
4-6 
8.6 

7  >  x 

5-2 
5-a 
2.9 

6.2 

•  5 
.  I 
•  3 

.  2 

6 

i  .4 
1.6 

2-5 

i  .  i 

2.2 

Cherry  Creek,  Colo.    .  .  . 

Canyort  City,       '     

Lamar,  Colo  

3-8 

4.8 

5-2 

7-3 

6.0 

7  -2 

Embudo,  New  Mexico..  . 

j   Fort  Bliss,  near  El   1 
Paso,  Texas  J  . 

Ternpe,  Ariz  

2.9 

1   6 

4-9 

10.9 
10.8 

10.  0 

5-5 

10.7 
xi.  7 

13-0 
Y.6 

9.6 
9.6 

12.5 
U-7 
6.6 

II.  4 
7.6 

xx.  9 
14.1 

9.2 
9.2 

II  .0 

5-8 

6.8 

6.S 
6.4 

5-2 

4.6 
3-7 

4.2 
4.4 
4-6 

2-9 

3-0 

2.9 

3.  a 

9r.6 

2.O 
2.7 
2.4 

2.O 

2.9 

3-2 

7-o 

!:i 

7-3 

7-4 
7-5 

s'-8 
4.2 

8  7 

" 

83.5 

3.9 

3-6 

i-l 

Florence,       

Yuma,           

80.0 

i   8 

7.2 

8.5 

7.  a 

7  O 

7-1 

4-3 

3.6 

2.5 

.5 

Bloods,  Cal  

Lake  Eleanor,  Cal  

Tuolumme  Mead,  Cal.  .  . 

Lake  Tenaiya,          "... 

5    7 

Little  Yosemite,       "    ... 

6     2 

generally  averaging  about  3  inches  less  than  the  corresponding 
evaporation  from  water  surfaces.  The  evaporation  from  sandy 
surfaces  was  found  to  be  only  about  one-fourth  to  one-fifth  that 
from  water.  Thus  in  the  observations  of  1873,  where  the  mean 
evaporation  from  water  was  20.4  inches,  that  from  earth  was 
17.9  inches  and  from  sand  3.7  inches.  Soil  cover  of  any  kind 
greatly  affects  the  amount  of  evaporation.  Assuming  the  evap- 
oration from  water  is  i.oo,  Prof.  B.  E.  Fernow  gives  it  for  bare 


28      EVAPORATION,  ABSORPTION,  AND  SEEPAGE 

soil  0.60;  sod  1.92;  cereals  1.73;  and  forest  1.51.  Evaporation 
from  ground  covered  with  forest  leaves  is  10  to  15  per  cent  and 
sand  33  per  cent,  when  from  bare  soil  it  is  100  per  cent. 

31.  Effect   of   Evaporation   on   Water   Storage. — The   value 
of  water  storage  for  irrigation  in  the  West  is  realized  chiefly 
between  May  and  August  inclusive.    The  only  loss  due  to  evapora- 
tion wkich  practically  affects  the  amount  of  storage  water  is 
that  occurring  during  these  months.     Little  or  no  rain  falls  in  the 
arid  region  during  this  period,  so  that  comparatively  little  of 
the  loss  of  evaporation  is  replaced  by  rain.     As  an  example,  take 
Central  California,  where  the  average  rainfall  during  these  months 
amounts  to  a  trifle  less  than  i  inch.     The  evaporation  during 
the  same  period  amounts  to  about  21  inches.     The  total  resultant 
deficiency  chargeable  to  evaporation  is  about  20  inches.     Storage 
reservoirs  in  the  West  are  frequently  at  high  altitudes  in  the 
mountains,  where  evaporation  is  less  than  in  the  hot  lowlands. 
At  Arrowhead  reservoir,  Cal.,  altitude  5160  feet,  the  measured 
evaporation  averages   36   inches  per  annum,   of    which    about 
40    per  cent    occurs  between  May  and  August,    the   irrigation 
season. 

32.  Percolation  and   its  Amount. — The  losses  due   to   per- 
colation in  canals  and  storage  reservoirs  are  very  considerable, 
and  added  to  those  due  to  evaporation  they  increase  the  total 
loss  by  from  25  to  100  per  cent  according  to  the  character  of 
the  soil.     It  is  difficult  to  ascertain  the  losses  due  to  percolation 
alone.     For  this  reason  it  is  desirable  to  consider  losses  from 
percolation  and  evaporation  together  and  include  them  under 
the  joint  head  of  "absorption." 

From  the  experiments  previously  alluded  to  which  were  con- 
ducted by  Mr.  Greaves  in  England,  it  was  found  that  while  the 
evaporation  from  earth  during  the  period  of  23  years  was  73.4 
per  cent  of  the  rainfall,  the  percolation  was  but  26.6  per  cent. 
From  sand  this  percentage  was  nearly  reversed,  the  loss  by  per- 
colation being  about  30  inches,  while  the  loss  by  evaporation  was 
but  7  inches.  There  was  no  loss  from  percolation  at  all  for  several 
consecutive  months.  As  an  average  year  take  that  of  1872, 
when  the  rainfall  amounted  to  23.8  inches  and  the  evaporation 


ABSORPTION  29 

from  water  20.4  inches,  the  losses  by  percolation  amounting  to 
4  inches  in  earth  and  20.1  inches  in  sand.  From  observations 
and  experiments  made  in  Bavaria  it  appeared  that  whereas  in 
the  warm  summer  months  the  depth  of  percolation  on  open  bare 
ground  was  u  per  cent  of  the  rainfall,  in  forests  it  amounted 
to  as  high  as  36  per  cent  of  the  rainfall. 

In  our  West  these  quantities  will  be  materially  different.  The 
amount  of  rainfall  is  relatively  small  on  the  ordinary  mountain 
catchment  basin.  The  slopes  are  steep  and  generally  rocky.  As 
a  result  of  this  the  percentage  of  percolation  will  be  low,  the 
amount  of  runoff  being  relatively  higher.  Where  there  are  dense 
forests,  the  soil  beneath  which  is  covered  with  a  depth  of  litter, 
or  where  the  slopes  are  low,  the  percentage  of  percolation  will 
be  relatively  high.  The  effect  of  vegetation  or  other  soil  cover 
on  percolation  is  to  reduce  the  latter,  being  thus  the  reverse  of  its 
effect  on  evaporation,  and  hence  nearly  balancing  its  net  effect  on 
absorption.  Wollny  found  the  percolation  from  loam  20  inches 
deep  to  be  33  per  cent  of  the  precipitation,  and  for  the  same 
covered  with  grass  1.3  per  cent.  For  sand  it  was  65  per  cent, 
and  for  the  same  grass  covered  14.0  per  cent. 

33.  Absorption. — Mr.  J.  S.  Beresford,  of  India,  argues  that  the 
losses  by  percolation  are  due  to  capillary  attraction  and  the  action 
of  gravity.  The  latter  takes  place  only  through  coarse  sand  or 
gravel,  while  the  former  is  a  more  complicated  process  acting 
where  the  particles  are  fine  and  in  close  contact  one  with  the  other. 
Capillary  attraction  stops  where  the  absorbing  medium  is  limited, 
for  as  soon  as  water  which  has  been  carried  by  its  action  through 
a  bank  reaches  the  outer  surface,  percolation  ceases  and  evapora- 
tion comes  into  play.  It  is  for  this  reason  that  banks  of  sand 
even  when  well  rammed  will  retain  water.  The  more  extensive 
the  absorbing  medium  the  greater  the  losses  from  this  cause; 
hence  the  loss  by  absorption  is  greater  when  a  canal  is  in  cutting 
than  when  in  embankment.  If  the  extent  of  the  absorbing 
medium  be  limited  by  a  bed  of  clay  placed  under  either  the  reser- 
voir or  canal  in  which  percolation  occurs,  then  the  losses  due 
to  this  cause  are  rapidly  diminished  in  quantity.  The  layer  next 
the  wetted  perimeter  limits  the  quantity  absorbed,  and  the  greater 


30      EVAPORATION,  ABSORPTION,  AND  SEEPAGE 

its  area  the  more  will  it  pass  through  to  the  still  greater  area 
of  the  next  layer ;  hence  percolation  varies  as  the  wetted  perimeter. 
34.  Amount  of  Absorption  in  Reservoirs  and  Canals. — 
The  volume  of  this  is  very  difficult  to  ascertain  and  varies  greatly 
with  soil  and  climate.  If  the  bottom  of  the  reservoir  is  com- 
posed of  sandy  soil,  the  losses  from  percolation  and  evaporation 
combined  will  be  about  double  those  from  the  latter  alone. 
Whereas,  if  the  bottom  of  the  reservoir  be  of  clayey  material,  or 
if  the  reservoir  be  old  and  the  percolation  limited  by  the  sediment 
deposited  on  its  bottom,  this  loss  may  be  but  little  more  than  that 
of  evaporation  alone. 

On  a  moderate-sized  canal  in  India  the  total  losses  due  to 
absorption  have  been  found  to  amount  to  about  one  second-foot 
per  linear  mile.  In  new  canals  these  losses  are  greatest.  If  the 
soil  is  sandy,  the  losses  on  new  canals  may  amount  for  long  lines 
to  from  40  to  60  per  cent  of  the  volume  entering  the  head.  In 
shorter  canals  the  percentage  of  loss  will  be  proportionately 
decreased,  though  it  will  rarely  fall  below  30  per  cent  in  new 
canals  of  moderate  length.  As  the  canal  increases  in  age  the 
silt  carried  in  suspension  will  be  deposited  on  its  banks  and 
bottom,  thus  filling  up  the  interstices  and  diminishing  the  loss. 
In  old  canals  with  lengths  varying  between  30  and  40  miles  the 
loss  may  be  as  low  as  12  per  cent  in  favorable  soil,  though  in 
general  for  canals  of  average  length  the  loss  will  be  about  20 
to  25  per  cent  of  the  volume  entering  the  head  (Art.  65).  On 
the  Ganges  canal  in  India,  the  length  of  which  is  several  hundred 
miles,  the  losses  in  some  years  have  been  as  high  as  70  per  cent. 
Experiments  made  on  Indian  canals  where  the  climate  and  soil 
are  similar  to  our  own  show  that  the  loss  by  evaporation  alone 
on  medium-sized  canals  is  about  5  per  cent  of  the  probable 
discharge,  showing  that  the  greater  portion  of  the  loss  by  absorp- 
tion is  from  percolation. 

35.  Prevention  of  Percolation. — An  excellent  method  for  the 
reduction  of  the  loss  by  percolation  is  that  recommended  by 
Mr.  Beresford  who  advises  that  pulverized  dry  clay  be  thrown 
into  the  canals  near  the  headgates.  This  will  be  carried 
long  distances  and  deposited  on  the  sides  and  bottom  of  the 


SEEPAGE   WATER  31 

canal,  forming  a  silt  berme.  The  losses  by  absorption  are 
greatly  increased  by  giving  the  canal  a  bad  cross-section.  Thus 
depressions  along  the  line  of  a  new  canal  are  often  utilized  to 
cheapen  construction  by  building  up  a  bank  on  the  lower  side 
only,  thus  allowing  the  water  to  spread  and  consequently  in- 
creasing the  absorption.  The  least  possible  wetted  perimeter 
and  the  least  surface  exposed  to  the  atmosphere  will  cause  the 
least  loss  from  this  cause. 

36.  Seepage  Water. — In   many  instances  where  canals  and 
reservoirs  are  bordered  by  steep  hillsides  the  amount  of  water 
lost  may  prove  to  be  much  less  than  would  be  expected.     This 
is  due  to  the  fact  that  large  amounts  of  seepage  water  may  enter 
the  canal  or  reservoir  from  the  surrounding  country  and  thus 
replenish  to  a  large  extent  the  losses  from  absorption. 

Before  irrigation  becomes  general  in  any  locality  it  is  fre- 
quently impossible  to  derive  any  water  from  wells,  as  the  sub- 
surface-water level  may  be  at  a  great  depth  below  the  surface. 
After  irrigation  has  been  practised  for  some  time,  however,  the 
soil  becomes  filled  with  water  and  the  subsurface  level  rises  so 
that  shallow  wells  often  yield  persistent  supplies.  In  portions 
of  California,  especially  in  the  neighborhood  of  Fresno,  where  the 
subsurface-water  level  was  originally  from  60  to  80  feet  below 
the  surface,  wells  10  and  15  feet  in  depth  now  receive  constant 
supplies,  the  result  of  seepage  from  the  canals.  Water  used  in 
irrigating  is  in  large  part  returned  to  the  drainage  channels  and 
can  be  again  diverted  for  irrigation. 

37.  Amount    of    Seepage    Water.— The    State    Engineer    of 
Colorado  conducted  measurements  of  seepage  water  returned  to 
the  South  Platte  and  Cache  la  Poudre  rivers  during  the  years 
1890  to  1893  inclusive.     These  showed  a  constant  increase  in 
the  amount  of  seepage  water  returned   to  these  streams  and 
available  for  diversion  below  the  points  of  measurement. 

On  the  South  Platte  River,  in  a  distance  of  397  miles,  the 
entire  gain  from  seepage  water  was,  in  1893,  573  second-feet, 
or  a  gain  of  430.5  per  cent  over  that  in  the  river  at  the  upper 
measuring  station.  In  other  words,  several  times  the  amount 
which  was  diverted  from  the  river  was  returned  to  it  through 


32      EVAPORATION,  ABSORPTION,  AND  SEEPAGE 

seepage  from  the  surrounding  country.  On  the  same  portion  of 
the  river  the  percentage  of  increase  in  1891  was  300,  or  three 
times  the  flow  at  the  first  measuring  station.  In  1891  the  average 
increase  from  seepage  on  the  South  Platte  was  3.24  second-feet 
per  mile.  In  1893  it  was  4.0  second -feet  per  mile,  but  was  as 
great  in  one  mile  as  13.7  second-feet,  varying  between  these  limits. 

On  the  Cache  la  Poudre,  experiments  made  in  1889  show  that 
while  the  original  discharge  at  the  canyon  was  127.6  second-feet, 
the  volume  at  a  point  considerably  lower  down  the  stream  had  in- 
creased to  214.7  second-feet,  after  supplying  fifteen  canals  and 
without  receiving  additional  natural  drainage.  Experiments 
on  the  same  river  during  succeeding  years  showed  similar  results. 
The  average  amount  of  seepage  water  returned  to  the  Cache  la 
Poudre  during  the  several  years  of  observation  was  2.4  second- 
feet  per  mile.  Seepage  losses  measured  in  canals  in  California 
were  i  to  5  second-feet  per  mile.  In  an  unusually  porous  canal 
near  Fresno  such  losses  amounted  to  15  second-feet  per  mile. 

Prof.  L.  G.  Carpenter  sums  up  his  investigations  on  this  subject 
thus :  "  There  is  real  increase  in  the  volumes  of  streams  as  they  pass 
through  irrigated  sections.  This  increase  is  approximately  pro- 
portional to  the  irrigated  area.  The  passage  of  seepage  water 
through  it  is  very  slow.  The  amount  of  seepage  water  slowly  but 
constantly  increases.  This  seepage  water  adds  to  the  amount 
of  culturable  land.  On  the  Cache  la  Poudre  River  about  30 
per  cent  of  the  water  applied  in  irrigation  is  returned  to  the  river." 

Investigations  of  a  similar  nature  conducted  by  the  Utah 
Agricultural  Experiment  Station  and  by  others  all  point  in  the 
same  direction.  The  amounts  of  returned  water  by  seepage 
indicated  in  the  above  experiments  must  not  be  taken  as  a  criterion 
of  what  may  be  expected  in  other  regions.  The  circumstances 
surrounding  these  cases  are  believed  to  be  especially  favorable 
for  the  return  of  seepage  water.  It  is  believed  that  from  this,  as 
almost  a  maximum,  the  amount  of  seepage  water  returned  may 
diminish  to  practically  nothing,  dependent  upon  the  soil,  quality 
of  underlying  strata,  their  slope  and  inclination,  and  the  area 
of  drainage  basin  above  and  tributary  to  them. 

Observations  made  at  storage  reservoirs  for  New  York  and 


WORKS    OF    REFERENCE  33 

Boston  and  some  other  Eastern  cities  show  clearly  that  the 
amount  of  seepage  water  returned  from  the  surrounding  country 
to  reservoirs  which  have  been  drawn  down  for  service  varies 
between  10  and  30  per  cent  of  their  capacities.  This  is  supposed 
to  be  largely  due  to  the  fact  that  the  water  plane  of  the  surround- 
ing country  is  filled  up  from  the  reservoir  as  well  as  from  seepage 
from  the  adjacent  country.  Measurements  of  volume  in  the 
Sweetwater  reservoir  in  Southern  California  show  that  after 
water  ceases  to  be  drawn  from  the  reservoir  it  begins  to  fill  up 
while  no  water  is  entering  from  streams,  thus  indicating  that 
similar  additions  from  seepage  may  be  anticipated  for  Western 
reservoirs.  As  a  result,  the  actual  available  capacity  of  a  storage 
reservoir  will  probably  be  found  to  be  greater  than  its  measured 
capacity  in  spite  of  the  losses  which  it  sustains  from  evaporation 
and  percolation.  It  will  perhaps  be  more  correct  in  designing 
reservoirs  to  assume  that  these  gains  and  losses  balance. 

38.  Works  of  Reference.     Evaporation,  Absorption,  Seepage. 

BERESFORD,  J.  S.     Memorandum  on  the  Irrigation  Duty  of  Water.     Prof.  Papers 

on  Indian  Engineering,  No.  212.     Roorkee,  India. 

BUCKLEY,  R.  B.     Irrigation  Works  in  India  and  Egypt.     E.  &  F.  N.  Spon,  Lon- 
don, 1893. 
CRAMER,   C.   B.     Seventh  Biennial   Report  of  State  Engineer.     Denver,   Colo., 

1894. 
EVANS,  John.     Percolation  of  Rainfall  on  Absorbent  Soils.     Trans.  Inst.  C.  E., 

vol.  45.     London,  1875. 
FITZGERALD,  DESMOND.     Evaporation.     Trans.  Am.  Soc.  C.  E.,  vol.   15.     New 

York,  1886. 
—  Rainfall,  Flow  of  Streams,  and  Storage.     Trans.  Am.  Soc.  C.  E.,  vol.  27. 

New  York,  1892. 
FORTIER,  SAMUEL.     Water  for  Irrigation.     Bulletin  26,  Agricultural  Experiment 

Station,  Logan,  Utah.     December,  1893. 
-  Preliminary  Report  on   Seepage  Water,   etc.     Bulletin   38,   Agricultural 

Experiment  Station,  Logan,  Utah.     February,  1895. 

Evaporation,  Bulletin  177,  Office  of  Experiment  Stations.     U.  S.  Depart- 


ment of  Agriculture.     Washington,  D.  C.,  1907. 

GREAVES,  CHARLES.     Evaporation  and  Percolation.     Trans.  Inst.  C.  E.,  vol.  45. 
London,  1875. 

MAXWELL,  J.  P.     Sixth  Biennial  Report  of  State  Engineer.     Denver,  Colo.,  1892. 

NEWELL,  F.  H.     Hydrography.     Parts  II  of  nth  to  i3th  Annual  Reports,  U.  S. 
Geological  Survey.     Washington,  D.  C.,  1891. 

SLIGHTER,  C.  S.     Motion  of  Underground  Waters.     Water-Supply  Paper  No.  67, 
U.  S.  Geological  Survey.     Washington,  D.  C.,  1902. 

WILSON,  H.  M.     Irrigation  in  India.     Part  II,  i2th  Annual  Report,  U.  S.  Geo- 
logical Survey.     Washington,  D.  C.,  1891. 
I 


CHAPTER  IV 

ALKALI,    DRAINAGE,    AND   SEDIMENTATION 

39.  Harmful  Effects  of  Irrigation. — When  irrigation  is  prac- 
tised without  proper  attention  to  drainage  it  is  liable  to  result  in 
the  following  evils:     (i)  production  of  alkali  or  flocculent  salts 
on  the  surface  of  the  ground;    (2)  souring  or  waterlogging  of 
the  soil  due  to  supersaturation ;    (3)  fevers  and  other  injurious 
effects,  the  result  of  the  same  cause. 

40.  Alkali. — The  white  efflorescent  salt  known  as  " alkali" 
is  to  be  found  in  many  portions  of  the  West,  both  as  the  result 
of  irrigation  and  occurring  naturally  over  extensive  areas.     This 
salt  has  been  analyzed  and  found  to  consist  chiefly  of  chloride 
(common  salt),  carbonate  (sal  soda),  and  sulphate  (Glauber's 
salt)  of  sodium.     The  relative  proportions  of  these  vary  greatly, 
but  the  latter  is  nearly  always  present  and  predominates,  rang- 
ing from  5  to  75  per  cent.     There  is  generally  also  present  a 
small  amount  of  accessory  salts,  as  manganese  sulphate  and 
the  salts  of  potassium.     Of  the  latter,  the  nitrates  and  phos- 
phates are  of  value,  as  they  are  the  ingredients  usually  supplied 
in  fertilizers.     Their  presence  therefore  indicates  the  occurrence 
of  sufficient  plant-food  in  the  soil  to  render  fertilization  unneces- 
sary. 

Perhaps  the  most  harmful  of  the  alkaline  salts  is  sodium 
carbonate,  commonly  called  "black  alkali."  This  is  more 
generally  found  in  the  warmer  climates  and  in  moist  close  soil, 
rich  in  humus,  such  as  is  found  in  the  San  Joaquin  valley  of 
California,  and  it  is  mainly  found  in  low  ground,  where  the 
alkali  occurs  in  spots.  It  is  greatest  in  amount  near  the  centre 
of  the  spots,  while  potash,  on  the  contrary,  increases  in  amount 
near  the  margin.  The  effect  of  alkali  is  to  kill  all  vegetable 
matter  and  to  render  the  soil  barren  and  unproductive. 

41.  Causes  of  Alkali.— Where  the  natural  drainage  of  the 

34 


WATERLOGGING  55 

country  is  defective  and  the  strata  underlying  the  surface  are 
impervious  or  the  soil  not  deep,  irrigation  or  rainfall  causes 
the  subsurface-water  plane  to  rise  to  such  a  height  that  finally 
the  soil  becomes  saturated.  Evaporation  then  takes  place  from 
the  surface,  and  as  this  process  continues  there  are  left  on  the 
soil  the  salts  contained  in  the  water.  Thus  the  more  water  that 
evaporates  from  the  surface  the  more  alkali  will  be  deposited, 
and  increased  rainfall  or  irrigation  will  increase  the  amount  of 
alkali.  It  is  thus  seen  that  the  direct  cause  of  the  production  of 
alkali  is  the  rise  of  the  subsurface-water  plane  due  to  defective 
drainage  and  its  evaporation  from  the  surface.  Seepage  from 
badly  constructed  canals  is  a  great  producer  of  alkali.  Thus 
where  the  velocity  of  the  canal  is  slow,  time  is  given  for  water  to 
soak  into  the  soil  and  permeate  it.  Prof.  E.  W.  Hilgard's  ex- 
periments show  that  the  main  mass  of  alkaline  salts  exists  in  the 
soil  within  a  short  distance  of  the  surface,  and  that  the  amount  of 
these  salts  is  limited.  He  therefore  asserts  that  the  bulk  of  alkali 
salts  is  accumulated  within  easy  reach  of  underdrains,  and  if 
once  removed  not  enough  to  do  harm  will  again  come  from 
below. 

42.  Waterlogging. — Where  the  rise  of  water  from  the  sub- 
surface or  its  addition  to  the  surface  from  natural  causes  or  ir- 
rigation is  more  rapid  than  the  losses  by  evaporation  or  drainage, 
the  water  stands  in  pools  and  the  soil  becomes  soft  and  marshy, 
producing  the  effect  known  as  "swamping"  or  "waterlogging." 
Like  alkali,  waterlogging  is  directly  traceable  to  defective  drain- 
age and  the  careless  use  of  water.     Where  the  conditions  are 
sufficiently  well  balanced  for  drainage  to  prevent  the  rise  of  the 
subsurface- water  to  within  10  or  15  feet  of  the  surface,  continued 
irrigation  produces  good  results  by  soaking  up  the  lower  strata 
and  giving  an  abundance  of  water  near  the  surface  for  wells  and 
for  moistening  the  deeper-rooting  plants. 

43.  Prevention  of  Alkali  and  Waterlogging. — Since  evapora- 
tion causes  the  rise  of  alkali,  evaporation  should  be  reduced  to 
the  lowest  point.     This  may  be  done  by  mulching  the  soil.     It 
is  also  possible  in  some  cases  to  cultivate  deep-rooting  plants  or 
such   as  shade  the  soil  and  reduce  the  amount  of  evaporation, 


36  ALKALI,    DRAINAGE,    AND    SEDIMENTATION 

or  such  as  are  least  harmfully  affected  by  its  presence,  thus  miti- 
gating the  evil  and  permitting  some  use  to  be  made  of  the  land. 
Irrigating  only  such  lands  as  have  good  natural  drainage,  and 
exercising  care  not  to  interfere  with  this,  is  one  of  the  best  and 
surest  preventives  of  the  production  of  alkali  and  waterlogging. 
The  introduction  of  artificial  drainage  produces  the  same  effect, 
while  in  a  lesser  degree  the  same  result  may  be  obtained  by  the 
use  of  deep  ditches  or  furrows  which  themselves  act  as  drainage 
channels.  When  the  quantity  of  alkali  is  small,  the  evil  effects 
resulting  from  its  presence  may  be  mitigated  by  the  application 
of  chemical  antidotes;  and,  lastly,  relief  may  be  obtained  in  some 
cases  by  watering  the  surface  and  drawing  off  the  water  without 
allowing  it  to  soak  into  the  ground.  This  system  of  reclaiming 
the  land  by  surface  washing  and  drawing  off  the  salt-impregnated 
water  is  known  as  ' '  leaching. ' '  One  of  the  most  effective  methods 
for  the  prevention  of  alkali  is  the  judicious  and  sparing  use  of 
water  in  irrigation  where  the  drainage  is  defective. 

As  a  result  of  his  investigations  in  northern  Africa,  Mr. 
Thomas  H.  Means  states  that  the  amount  of  soluble  matter  allow- 
able in  an  irrigation  water  has  been  greatly  underestimated,  and 
that  many  sources  of  water  which  have  been  condemned  can  be 
used  with  safety  and  success  with  proper  precautions.  The  Arabs 
in  the  Sahara  successfully  grow  vegetables  with  water  containing 
as  high  as  800  parts  of  soluble  salts  to  100,000  parts  of  water, 
sometimes  50  per  cent  of  the  salts  being  sodium  chloride.  The 
Arab  gardens  consist  of  small  plots  20  feet  square,  between  which 
are  drainage  ditches  dug  to  a  depth  of  about  3  feet.  This  ditch- 
ing at  short  intervals  insures  rapid  drainage.  Irrigation  is  by 
the  check  method  and  application  made  at  least  once  a  week, 
sometimes  oftener.  A  large  quantity  of  water  is  used  at  each 
irrigation,  thus  securing  the  continuous  movement  of  the  water 
downward,  permitting  little  opportunity  for  the  soil  water  to 
become  more  concentrated  when  the  irrigation  water  is  applied, 
and  there  is  little  accumulation  of  salt  from  the  evaporation  at 
the  surface.  What  concentration  or  evaporation  accumulation 
does  occur  is  quickly  corrected  by  the  succeeding  irrigation. 

44.  Chemical  Treatment. — A  cheap  antidote  for  many  alkaline 


CHEMICAL   TREATMENT  37 

salts  is  common  lime,  while  neutral  calcareous  marl  will  answer 
in  some  cases.  When  the  alkali  consists  of  carbonates  and 
borates,  the  best  antidote  is  gypsum  or  plaster  of  Paris.  Notable 
experiments  have  been  made  by  Prof.  E.  W.  Hilgard,  which  prove 
the  value  of  gypsum  in  neutralizing  the  " black  alkali,"  or  car- 
bonate of  soda.  In  the  case  of  this  alkali — one  of  the  worst- 
mulching,  deep  tillage,  suitable  plant-growth,  or  any  other 
corrective  except  gypsum  is  practically  unavailing.  Little  benefit 
is  to  be  expected  from  gypsum  in  the  case  of  "white"  or  neutral 
alkali,  which  does  little  harm,  however,  under  proper  tillage;  but 
a  soil  heavily  tainted  with  black  alkali  can  be  rendered  profusely 
productive  by  the  use,  once  for  all,  of  a  ton  of  gypsum  per  acre. 
This  is  more  effective  when  applied  at  the  rate  of  about  500  pounds 
per  acre  per  annum  in  connection  with  some  seeding  at  the  same 
time,  for  the  slightest  growth  aids  in  shading  the  ground  and 
preventing  an  injurious  release  of  salts  by  evaporation.  Gypsum, 
however,  cannot  be  used  on  alkali  without  water;  its  action  must 
be  continued  for  several  months  and  through  two  or  three  seasons ; 
it  takes,  moreover,  several  weeks  before  immunity  is  secured,  and 
therefore  the  dressing  of  gypsum  should  be  applied  in  ample  time 
before  the  seeding;  and  thereafter  the  soil  must  be  well  cultivated 
and  ploughed  in,  and  promptly  followed  by  irrigation. 

Where  there  is  not  a  good  natural  drainage,  underdrains 
must  be  provided  in  reclaiming  alkaline  soil  by  chemical  treat- 
ment. Gypsum  acts  practically  by  converting  the  harmful  car- 
bonate of  sodium  into  the  less  harmful  sulphate  of  sodium  in 
the  presence  of  water  and  with  the  aid  of  thorough  mixing  by 
ploughing,  and  these  salts  are  washed  through  the  soil  and  are 
carried  off  into  natural  drainage  channels,  or,  if  the  locality 
treated  be  a  sink,  concentrated  in  its  bottom.  A  cheap  form 
of  underdrain  consists  of  boards  placed  together  like  the  letter  A, 
at  a  depth  of  about  3  feet  beneath  the  surface.  These  drains 
should  discharge  either  into  the  sink-hole  or  drainage  channel. 
Such  drains  can  be  constructed  for  about  $30  per  acre.  Mere 
surface  treatment  without  drainage,  in  soils  strongly  impregnated 
with  black  alkali,  would  change  the  latter  to  white  alkali,  but 
would  still  leave  too  much  of  this  in  the  soil  for  the  growth  of 


38  ALKALI,    DRAINAGE,    AND    SEDIMENTATION 

useful  vegetation.     Wherever  black  alkali  exists  the  use  of  stable 
manure  is  harmful  by  setting  free  corrosive  ammonia  vapors. 

45.  Mulching  and  Leaching. — An  excellent  preventive  against 
evaporation  from  the  soil  surface  and  the  consequent  production 
of  alkali  is  by  "mulching."     The  best  mulch  is  a  well  and  deep 
tilled  surface  soil,  which  is  kept  so  constantly  stirred  that  a  crust 
is  never  allowed  to  form.     As  a  result  evaporation  is  reduced  to 
a  minimum,  and  the  alkali  remains  distributed  throughout  the 
whole  of  the  tilled  layer  instead  of  as  a  hard  crust  at  the  surface 
where  the  bulk  of  the  damage  is  done.     Ploughing  in  large 
quantities  of  straw  produces  also  an  effective  mulch,  since  the 
straw  keeps  the  surface  loose  and  enables  the  grain  to  germinate. 
The  depth  or  thickness  of  this  protective  tilled  layer  is  of  the 
utmost  importance,  for  thereby  the  strong  surface  alkali  is  diluted 
with  the  largest  possible  mass  of  subsoil.     After  a  proper  tilling 
to  a  depth  of,  say,  10  to  12  inches,  it  requires  a  long  time  for 
the  salts  to  come  to  the  surface  again  in  sufficient  amount  to  injure 
the  crop. 

Leaching  is  not  infrequently  employed,  more  especially  in 
Europe,  to  mitigate  the  harmful  effects  of  alkali.  This  is  practised 
by  building  temporary  embankments  around  the  land  and  then 
flooding  it,  after  which  the  salt-impregnated  waters  are  rapidly 
drawn  or  pumped  off. 

46.  Growth  of  Suitable  Plants. — One  of  the  most  effective 
plants  which  can  be  grown  on  slightly  alkaline  soil  is  alfalfa, 
which  when  once  established  brings  to  bear  the  action  of  deep 
roots  and  dense  shade,  and  thus  by  repression  of  surface  evapora- 
tion tends  to  restore  the  soil  to  its  natural  condition.     Where 
mulching  is  practised  it  is  desirable  to  grow  hoed  crops,  such 
as  beans,  beets,  potatoes,  corn,  onions,  and  canaigre,  choosing 
preferably  the  deeper-rooted  of  these. 

Experiments  recently  conducted  by  Mr.  M.  E.  Jaffa  indi- 
cate that  Australian  salt-bush  is  likely  to  prove  one  of  the  most 
desirable  forage  plants  for  growth  on  alkali  soils.  It  is  readily 
eaten  by  stock,  is  rich  in  digestible  nutrients,  and  has  been  suc- 
cessfully grown  on  alkaline  land  which  will  produce  no  other 
crop.  This  plant  is  wonderful  for  its  productiveness  and  its 


DRAINAGE  39 

drought-resisting  power.  It  is  prostrate  in  its  growth,  covering 
the  ground  with  a  green  cushion  8  to  10  inches  thick,  and  thus 
effectually  shading  it.  It  is  perennial,  and  when  cut  soon  re- 
produces itself  from  the  same  root.  Its.  yield  per  acre  is  very 
large,  being  about  the  same  as  that  of  alfalfa. 

47.  Drainage. — Generally    the    drainage    of   irrigated  land 
will  take  care  of  itself  if  the  natural  drainage  channels  are  not 
interfered  with  or  obstructed.     Where  the  surface  has  a  mod- 
erate though  sufficient  slope  to  allow  the  water  to  flow  off,  or 
the  soil  is  underlain  by  deep  beds  of  gravel  or  porous  rocks  which 
will  carry  off  the  percolation  water,  irrigation  may  be  practised 
for  all  time,  and  even  an  excessive  amount  of  water  may  be  used 
without  seriously  affecting  the  crops.     In  some  cases  the  drainage 
may  be  improved  by  digging  drainage  channels  or  ditches  or  laying 
drainage  pipes  under  the  surface. 

In  many  portions  of  the  West,  and  especially  in  the  San 
Joaquin  valley  in  California,  old  sloughs  and  abandoned  natural 
drainage  lines  have  been  utilized  as  irrigation  channels.  The 
effect  is  bad,  as  the  natural  drainage  lines  thus  become  over- 
loaded, resulting  in  waterlogging  the  soil.  In  this  way  large 
areas  in  Fresno  County  and  its  neighborhood  have  been  rendered 
uncultivable,  whereas  with  a  proper  system  of  irrigating  channels, 
providing  the  natural  drainage  channels  had  been  left  open,  no 
evil  effects  would  necessarily  have  resulted. 

In  most  regions  where  the  slopes  are  very  slight,  as  in  river 
bottoms  and  where  irrigation  has  been  practised  for  many  years, 
like  Lombardy,  Italy,  and  in  the  lower  San  Joaquin  valley, 
California,  drainage  becomes  quite  as  important  as  irrigation, 
and  it  is  extremely  necessary  to  provide  some  means  of  conducting 
seepage  water  to  the  streams.  In  some  places  where  the  streams 
flow  in  channels  above  the  surrounding  land  it  is  even  necessary 
to  build  dikes  to  confine  the  seepage  water  and  to  pump  this 
back  to  the  streams. 

48.  Excessive  Use  of  Water. — This  is  one  of  the  greatest 
evils  at  present  noticeable  in  our  western  irrigation  methods. 
Almost   invariably  too   much  water  is   employed   in   irrigating 
crops.     The  result  is  waste  of  water  and  oversaturation  of  the 


40  ALKALI,    DRAINAGE,    AND    SEDIMENTATION 

soil.  As  the  value  of  water  rises  it  will  be  used  with  less  ex- 
travagance. Proper  care  in  the  location  and  construction  of 
the  canal  banks  will  aid  greatly  in  reducing  the  evil  effects  of 
irrigation.  If  the  location  is  bad,  the  natural  drainage  channels 
may  be  interfered  with.  If  the  construction  is  bad,  the  loss  by 
seepage  from  the  canal  into  the  soil  becomes  great.  With  proper 
drainage  too  much  water  cannot  be  used. 

49.  Silt. — Great  volumes  of  silt  are  transported  by  Western 
rivers  in  times  of  flood — a  result  chiefly  of  the  erosion  of  the 
alluvial  banks  of  the  stream  and  its  tributaries.     The  heavier 
sand  and  gravel  is  usually  deposited  in  the  upper  reaches  of 
the  stream,  and  the  great  bulk  of  the  silt  reaching  the  canals 
is  of  the  finest  quality.     As  the  velocity  in  the  canals  is  relatively 
slow,  much  of  the  matter  carried  in  suspension  is  deposited  near 
their  heads,  or  in  storage  reservoirs  or  other  slack  water,  thus 
diminishing  the  discharge  of  the  canal  or  the  volume  of  the  reser- 
voir. 

Silt  consists  of  both  organic  and  mineral  matter,  and  while 
the  former  especially  is  often  a  source  of  advantage  to  the  crops, 
it  is  generally  a  great  cause  of  trouble  in  the  irrigation  channels. 
It  is  desirable  to  pass  forward  to  the  fields  as  much  of  the  fertiliz- 
ing matter  carried  in  suspension  as  possible,  and  at  the  same 
time  to  prevent  the  deposition  of  sediment  in  the  canal.  This 
result  is  brought  about  by  various  devices  in  the  construction 
of  the  canal  headworks  whereby  the  heavier  sands  and  gravels 
are  deposited  just  in  front  of  diversion  weirs  or  carried  through 
undersluices  in  these,  or  are  deposited  in  the  upper  reaches  of 
the  canals,  whence  they  can  be  readily  flushed  by  sand  gates  and 
escapes,  or,  if  no  other  means  of  removal  be  practicable,  by 
dredging. 

50.  Character    of    Silt. — Silt    varies    greatly    in    its    nature, 
depending  chiefly  upon  the  velocity  of  the  stream  and  upon 
the  soil  and  topography  of  its  catchment  basin.     In  the  upper 
reaches  of  a  stream  where  the  slopes  are  great,  the  fall  of  the 
stream  bed  rapid,  and  the  velocity  correspondingly  high,  the 
sediment  moved  by  the  water  consists  chiefly  of  bowlders,  shingle, 
and  large  gravel.     Much  of  this  is  not  actually  carried  in  sus- 


AMOUNT   OF    SILT 


pension,  but  is  merely  rolled  along  the  stream  bed.  Lower 
down  on  the  same  stream,  where  the  velocity  is  4  to  7  feet  a  second, 
the  sediment  consists  chiefly  of  coarse  sand  or  mud,  the  former 
of  which  is  usually  near  the  bed  and  is  rather  rolled  upon  it  than 
carried  in  suspension.  Still  lower  down  on  such  a  stream,  or 
in  canals  the  velocities  of  which  are  but  2  or  3  feet  a  second, 
only  the  finest  silt,  rich  in  organic  matter,  is  carried  in  suspension. 
51.  Amount  of  Silt. — The  amount  of  sediment  which  is 
carried  in  suspension  during  floods  is  greater  than  is  usually 
appreciated.  From  investigations  made  by  the  United  States 
Geological  Survey  on  the  Rio  Grande  in  1889,  it  was  found  to 
range  from  J  to  J  of  i  per  cent  of  the  volume  of  flow.  It  was 
also  estimated  that  in  about  one  hundred  and  fifty  years  the 
amount  of  this  sediment  would  seriously  impair  a  reservoir  60 
feet  in  depth.  On  the  American  River  at  Folsom,  California, 
in  a  single  year  a  depth  of  nearly  10  feet  of  wet  silt  was  deposited 
in  a  reservoir  situated  at  that  point.  Much  of  this,  however, 
was  heavy  matter,  bowlders  and  gravel  rolled  along  the  stream 
bottom  by  the  swift  current.  Mr.  R.  B.  Buckley  states  that 
the  proportion  of  silt  to  water  by  weight,  in  several  rivers,  is  as 
follows : 


Mississippi i  to  572 

Rhone,  France  (velocity  8  feet 

per  second) i  to     45 

Po,  Italy i  to  300 


Rhine,  Germany i  to  100 

Indus,    India    (velocity    from 

3$  to  5  feet  per  second).,    i  to  237 


The  amount  of  sediment  deposited  in  reservoirs  by  turbid 
streams  may  be  so  great  as  materially  to  reduce  their  capacities 
in  a  few  years.  Careful  tests  must,  therefore,  be  made  to  de- 
termine the  possible  amount  of  this  and  its  effect.  In  twelve 
years  the  amount  of  sediment  deposited  in  Sweetwater  reservoir, 
Cal.,  was  900  acre-feet.  In  that  time  1 80, coo  acre-feet  of 
water  had  entered  the  reservoir.  The  amount  of  measured 
solids  deposited  thus  averaged  about  half  of  one  per  cent.  Care- 
ful sampling  of  the  Gila  River  water,  Arizona,  to  determine  the 
possible  life  of  a  reservoir  of  174,000  acre-feet  capacity  developed 
the  fact  that  the  mud  carried  in  suspension  in  a  year  averaged 
10.5  per  cent,  and  the  amount  of  solids  2  per  cent.  In  a  year 


42  ALKALI,    DRAINAGE,    AND    SEDIMENTATION 

this  reservoir  would  accumulate  9597  acre-feet  of  solid  sediment, 
and  its  life  would  be  but  18^  years, 

On  the  Soane  canal  in  India,  which  is  diverted  from  a  river 
having  a  maximum  velocity  of  7.5  feet  per  second,  as  much  as 
from  3  to  5  feet  of  sand  and  coarser  material  is  deposited  in  the 
first  quarter  mile  of  the  canal,  gradually  diminishing  in  depth 
until  but  a  few  inches  are  deposited  at  5  or  6  miles  from  its  head. 

As  already  stated,  the  greater  proportion  of  the  silt  is  heavy 
matter  floating  near  or  rolled  along  the  bottom ;  and  as  shown 
by  experiments  conducted  on  the  Rhine  with  a  flood  velocity 
of  8  feet  per  second,  this  silt  near  the  bottom  was  as  much  as 
88  per  cent  greater  in  amount  than  that  at  the  surface.  It 
was  observed  also  that  there  is  more  silt  in  a  rising  flood  than 
in  a  falling  one,  and  the  maximum  amount  of  silt  is  carried  when 
the  flood  has  reached  about  two-thirds  of  its  height.  It  is  be- 
cause of  this  reason  that  under-sluices  in  storage  dams  (Arts. 
1 86  and  347)  are  of  value,  as  the  water  may  be  permitted  to 
waste  through  these  until  the  maximum  flood  height  has  been 
reached,  after  which  they  may  be  closed  and  the  remaining 
flood  waters,  which  are  less  heavily  charged  with  silt,  be  stored. 

52.  Prevention  of  Sedimentation  in  Reservoirs  and  Canals. 
— In  view  of  the  important  bearing  which  sediment  carried 
in  suspension  has  upon  irrigation  water,  it  is  necessary  to  con- 
sider the  quality  and  amount  of  sediment  in  the  source  of  water 
supply  of  any  irrigation  work.  Where  a  canal  is  taken  from  a 
stream  of  high  velocity,  which  usually  carries  but  little  fertilizing 
material  and  much  heavier  matter,  it  is  necessary  to  design  the 
head  works  in  such  manner  that  most  of  this  shall  be  excluded,  and 
to  cause  the  deposition  of  the  remainder  in  a  short  distance  in 
the  upper  reaches  of  the  canal.  With  streams  of  lower  velocity, 
the  problem  to  be  solved  is  usually  how  to  align  the  canals  and 
distributaries  and  choose  their  slopes  and  velocities,  so  that  the 
heavier  particles  which  are  suspended  near  the  bed  of  the  stream 
shall  be  deposited  close  to  the  headworks  of  the  canal,  while  the 
lighter  silt  containing  the  fertilizing  properties  shall  remain  in  sus- 
pension until  deposited  on  the  fields. 

There    are    practically  but   twro   methods  of  mitigating  the 


PREVENTION    OF    SEDIMENTATION  .43 

injury  due  to  sedimentation  in  reservoirs.  One  is  by  building 
higher  up  on  the  stream  cheap  settling  reservoirs  which  may 
be  destroyed  in  the  course  of  a  number  of  years,  or  the  dams 
may  be  increased  in  height  as  they  silt  up.  The  other  method 
is  by  the  construction  of  under-  or  scouring-sluices  in  the  bottom 
of  the  dam.  These  have  not  as  yet  proved  effectual,  as  their 
influence  is  felt  at  but  a  short  distance  back  from  the  opening. 
Experience  has  shown  that  they  do  not  remove  silt  which  has 
already  been  deposited,  but,  providing  their  area  is  large  compared 
with  the  flood  volume  of  the  stream,  they  may  effectively  prevent 
the  deposition  of  sediment  by  permitting  the  silt-laden  waters  to 
flow  through  the  reservoir;  the  latter  being  filled  only  after  the 
flood  has  subsided  and  the  waters  become  less  turbid. 

Canals  should  be  so  designed  that  the  angle  at  which  they 
are  diverted  from  the  main  stream  shall  be  such  as  to  cause  the 
least  back  eddy  in  front  of  the  headgates  and  the  least  deposit 
at  that  point.  Where  a  canal  is  taken  off  at  right  angles  to  the 
line  of  the  stream  and  scouring-sluices  are  placed  in  the  weir 
immediately  adjacent  to  the  headgates,  the  main  stream  may 
be  so  trained  as  to  have  a  straight  sweep  past  the  headgates, 
and  thus  scour  out  any  deposits  occurring  at  that  point. 

As  the  velocity  of  the  current  is  generally  diminished  in 
the  upper  portion  of  the  canal  in  its  passage  from  the  main 
stream,  the  deposit  of  silt  is  likely  to  occur  at  this  point.  It  may 
be  well  to  encourage  this  by  increasing  the  cross-section  of  the 
canal  and  reducing  its  grade  so  that  its  capacity  shall  remain 
the  same  but  its  velocity  be  diminished.  Then  the  deposit  of 
silt  will  all  occur  in  the  first  half-mile  or  less  of  the  canal,  and 
it  may  be  either  dredged  out  or  perhaps  scoured  out  by  an  escape. 

Several  methods  of  removing  silt  from  canal  waters  have  been 
practised  in  India  for  a  number  of  years.  The  older  and  least 
satisfactory  is  by  digging  borrow-pits  in  the  bed  of  the  canal,  the 
reduction  of  velocity  over  these  causing  some  deposition.  Another 
is  by  the  construction  of  external  parallel  canals,  with  cross- 
banks  at  4000  to  5000  feet  intervals,  with  head  inlets  and  tail 
outlets,  the  whole  canal  supply  being  passed  through  these.  The 
velocity  being  reduced  causes  deposition,  thus  making  of  them 


44  ALKALI,    DRAINAGE,    AND    SEDIMENTATION 

settling-basins.  The  most  satisfactory  system  and  that  more 
generally  employed  consists  in  building  the  canal  banks  back 
from  the  channel,  with  low  spur-berms  extending  inward  to  the 
margin  of  the  channel  or  future  inner  bank.  The  effect  of  these 
spurs  is  to  shallow  the  water  flowing  over  them  and  reduce  the 
velocity  between  them,  causing  the  deposition  of  silt. 

53.  Fertilizing    Effects    of    Sediment. — The    value    of    silt- 
bearing  water  as  a  fertilizer  is  well  known.     In  the  valley  of  the 
Moselle,  France,  on  land  absolutely  barren  and  worthless  with- 
out fertilization,  the  alluvial  matter  deposited  by  irrigation  from 
turbid  water  renders  the  soil  capable  of  producing  two  crops  a 
year.     In  the  valley  of  the  Durance,  France,  the  turbid  waters  of 
that  stream  bring  a  price  for  irrigation  which  is  ten  or  twelve 
times  greater  than  that  paid  for  the  clear  cold  water  of  the  Sorgues 
River.     It  has  been  estimated  that  on  the  line  of  the  Galloway 
canal  in  California,  land  which  has  been  irrigated  with  the  muddy 
river  water  gives  18  per  cent  better  results  after  the  fifth  year  than 
the  same  land  which  has  been  irrigated  with  clear  artesian  water. 

54.  Weeds. — When   from   any   cause   it   becomes   necessary 
to  give  a  canal  a  low  velocity,  the  growth  of  water-weeds  and 
the  deposition  of  silt  are  encouraged.     Water-plants  grow  most 
freely  where  the  current  has  a  slow  velocity  and  the  depth  is 
such   that   the  sunshine  reaches  the  bottom.     They  thrive  in 
shallow    reservoirs,    thus    diminishing    their    capacity.     Brush, 
willows,  weeds,  and  rushes,  may  encroach  on  the  channels  of 
canals,  where  the  slopes  of  the  banks  are  low,  and  so  diminish 
the  waterway  as  to  reduce  greatly  the  carrying  capacity  of  the 
canal.      Provided  a  high  velocity  cannot  be  given,  the  only  pos- 
sible way  of  remedying  this  is  to  draw  off  the  water  and  destroy 
the  plants.    On  the  Pavia  canal,  Italy,  the   growth  of  aquatic 
plants  is  so  rank  as  to  require,  in  addition  to  two  annual  clearings, 
chiefly  for  silt,  the  constant  use  of  floating  cutting-machines. 

55.  Malarial  Effects  of  Irrigation. — In  numerous  localities, 
both  abroad  and  in  the  West,  irrigation  has  been  denounced  as 
a  serious  menace  to  the  health  of  the  community  because  of  the 
creation  of  swamps  and  their  malarial  effects.     From  careful 
researches,  both  by  a  committee  to  the  Indian  Government  and 


MALARIAL   EFFECTS   OF   IRRIGATION  45 

by  Dr.  H.  O.  Orme  of  the  California  State  Board  of  Health,  it 
appears  that  these  evil  effects  have  been  exaggerated,  and  may  be 
avoided,  either  by  more  sparing  use  of  water,  by  proper  drainage, 
or  by  abandoning  irrigation  in  limited  localities  which  it  is  im- 
possible properly  to  drain.  In  Southern  California,  between 
Los  Angeles  and  San  Diego,  where  the  natural  drainage  is  of 
the  best,  the  soil  as  a  rule  sandy  or  gravelly  and  open  to  a  great 
depth,  the  water  used  in  irrigation  sinks  into  the  ground  or  drains 
off,  and  the  use  of  almost  any  amount  of  water  does  not  breed 
malarial  mosquitoes.  On  the  other  hand,  in  such  regions  as  the 
low-lying,  comparatively  level  lands  of  the  lower  part  of  the 
Sacramento  and  San  Joaquin  valleys,  where  the  soil  is  heavy, 
the  slopes  slight,  and  the  underdrainage  poor,  it  is  undoubtedly 
true  that  irrigation  has  developed  various  disorders,  by  raising 
the  subsurface  water-plane,  thus  causing  the  water  to  stand 
in  swamps  or  stagnant  pools,  breeding  malarial  mosquitoes. 

Malarial  effects  are  not  attributable  directly  to  the  results 
of  irrigation  where  economically  and  properly  practised,  but 
are  frequently  due  to  carelessly  constructed  canal  works  having 
intercepted  the  natural  drainage,  thus  forming  swampy  tracts.  It 
appears  certain  that  when  care  is  taken  to  irrigate  only  land 
which  has  an  open  soil  and  such  slopes  and  natural  drainage  as 
to  prevent  waterlogging,  no  unhealthy  effects  will  result  from 
irrigation;  also,  that  when  malarial  influences  are  developed  by 
irrigation  their  effect  is  almost  strictly  local. 

It  is  desirable,  in  order  to  mitigate  the  possible  evil  effects 
of  irrigation,  to  keep  the  canal  as  much  as  possible  within  soil 
so  that  its  surface  level  may  be  low,  and  thus  only  raise  the  sub- 
surface water-plane  to  the  least  height  practicable;  that  earth 
wanted  to  complete  embankments  be  never  taken  from  exca- 
vations or  borrow-pits  except  where  such  localities  admit  readily 
of  drainage;  that  the  canal  and  its  branches  be  aligned  as  far  as 
possible  along  the  watershed  of  the  country  so  as  not  to  interfere 
with  drainage.  If  wholesome  water  and  not  open-ditch  water 
be  provided  for  domestic  uses,  prejudical  effects  of  irrigation 
are  largely  averted.  In  such  climates  as  will  encourage  its  growth 
it  appears  that  the  Eucalyptus  globulus  has  proved  beneficial 


46  ALKALI,    DRAINAGE,    AND    SEDIMENTATION 

in  mitigating  the  malarial  effects  of  irrigation  waters,  chiefly 
because  of  the  great  absorbing  and  transpiring  power  due  to 
its  rapid  growth.  The  destruction  of  mosquito  larvae  will  en- 
tirely remove  the  source  of  malarial  disorders. 

56.  Works  of  Reference.     Alkali,  Drainage,  and  Sedimenta- 
tion. 

BUCKLEY,  R.  B.  Irrigation  Works  in  India  and  Egypt.  E.  &  F.  N.  Spon.  Lon- 
don, 1893. 

DAVIS,  ARTHUR  P.  Report  on  Irrigation  Investigation,  etc.  Senate  Doc.  No. 
27,  Fifty-fourth  Cong.,  2d  Ses.  Washington,  D.  C.,  1896. 

DEAKIN,  ALFRED.  Royal  Commission  on  Water  Supply.  First  and  Fourth 
Progress  Reports:  Irrigation  in  Western  America,  Egypt,  and  Italy.  Mel- 
bourne, 1884. 

HILGARD,  E.  W.  Alkali  Lands.  Report  of  University  of  California.  Sacra- 
mento, 1886. 

-  Distribution  of  Salts  in  Alkali  Soils.     Bulletin  108,  Univ.  of  Cal.  Agri. 
Exper.  Station.     Berkeley,  1895. 

Report  of  the  Work  of  Agricultural  Experiment  Stations.     Univ.  of  Cal. 


Sacramento,  1894. 
JAFFA,  M.  E.     Australian  Salt-bush.     Bulletin  105,  Univ.  of  Cal.  Agric.  Exper. 

Station.     Berkeley,  1894. 
WILSON,  HERBERT  M.     Irrigation  in  India.     Part  II  of  i2th  Am.  Report  of  U.  S. 

Geological  Survey.     Washington,  D.  C.,  1891. 


CHAPTER  V 

QUANTITY   OF    WATER    REQUIRED 

57.  Duty  of  Water. — The  duty  of  water   may  be  defined 
as  the  ratio  between  a  given  quantity  of  water  and  the  area  of 
crop  which  it  will  mature.     In  order  to  determine  what  amount 
of  water  is  sufficient  to  irrigate  a  given  area  of  land  it  is  first 
necessary  to  determine  at  least  approximately  its  duty  for  the 
specific  case  under  consideration.     On  the  duty  of  water  depends 
the  financial  success  of  every  irrigation  enterprise,  for  as  water 
becomes  scarce  its  value  increases.     In  order  to  estimate  the 
cost  of  irrigation  in  projecting  works,  it  is  essential  to  know  how 
much  water  the  land  will  require.     In  order  to  ascertain  the 
dimensions  of  canals  and  reservoirs  for  the  irrigation  of  given 
areas  the  duty  of  water  must  be  known. 

58.  Units  of  Measure  for  Water  Duty  and   Flow. — Before 
considering  the  numerical  expression  of  water  duty,  the  standard 
units  of  measurement  should  be  defined.     For  bodies  of  standing 
water,  as  in  reservoirs,  the  standard  unit  is  the  " cubic  foot." 
In  the  consideration  of  large  volumes  of  water,  however,  the 
cubic  foot  is  too  small  a  unit  to  handle  conveniently,  and  the 
"acre-foot" — which   is   the  amount   of   water   that   will   cover 
one  acre  of  land  one  foot  in  depth,  that  is,  43,560  cubic  feet — is 
preferable,  especially  as  it  bears  a  direct  relation  to  the  unit 
used  in  defining  areas  cultivated.     Hence  the  capacity  of  a  reser- 
voir in  acre-feet  expresses  a  direct  ratio  to  the  number  of  acres 
which  it  will  irrigate,  or  its  duty  per  acre-foot.     In  considering 
running  streams,  as  rivers  or  canals,  the  expression  of  volume 
must  be  coupled  with  a  factor  representing  the  rate  of  movement. 
The  time  unit  usually  employed  by  irrigation  engineers  is  the 
second,  and  the  unit  of  measurement  of  flowing  water  is  the  cubic 
foot  per  second,  or  the  "  second  -foot,"  or  "cusec"  as  it  is  called 
for  brevity.     Thus  the  number  of  second-feet  flowing  in  a  canal 

47 


48  QUANTITY   OF    WATER   REQUIRED 

is  the  number  of  cubic  feet  which  pass  a  given  point  in  a  second 
of  time.  A  unit  still  employed  in  the  West  is  the  "miner's 
inch."  This  varies  greatly  in  different  localities,  and  is  denned 
by  State  statute.  In  California  one  second-foot  of  water  is  equal 
to  about  40  miner's  inches,  while  in  Colorado  it  is  equivalent  to 
about  38.4  miner's  inches.  The  period  of  time  during  which 
water  is  applied  to  the  land  for  irrigation  from  the  time  of  the 
first  watering  until  after  the  last  watering  of  the  season  is  known 
as  the  "irrigating  period."  This  is  generally  divided  into  several 
"service  periods,"  by  which  is  meant  the  time  during  which 
water  is  permitted  to  flow  on  the  land  for  any  given  watering. 

Each  method  of  expressing  duty  is  readily  convertible  into 
the  other,  providing  the  irrigating  period  be  known.  The  fol- 
lowing simple  formulas  are  given  by  Mr.  R.  B.  Buckley  for  use 
in  making  such  conversions  : 

Z>  =  duty  of  water  in  second-feet; 

B  =  irrigating  period  per  second-foot  ; 

V  =  cubic  feet  of  water  required  to  mature  one  acre  of  crop  ; 

5  =  total  depth  in  inches  of  volume  used  if  evenly  distributed  over 

area  irrigated; 
Q  =  discharge  in  second-feet  required  to  irrigate  a  given  area 

(A),  with  a  given  duty  (Z>),  and  irrigating  period  (B}. 

~n 

F=  —  X  86,400  ......      (4) 

5=^X23.8  ........     (5) 


D      23.8.8 
The  following  are  a  few  convenient  equivalents: 

TABLE  VII. 

UNITS    OF    MEASURE. 

i  second-foot  equals  40  California  miner's  inches  (law  of  March  23,  1901). 
i  second-foot  equals  38.4  Colorado  miner's  inches. 
i  second-foot  equals  40  Arizona  miner's  inches. 

i  second-foot  equals  7.48  United  States  gallons  per  second;   equals  448.8  gal 
lons  per  minute;   equals  646,272  gallons  for  one  day. 


UNITS   OF   MEASURE    FOR   WATER   DUTY   AND   FLOW      49 

TABLE  VII — Continued. 

i  second-foot  equals  6.23  British  imperial  gallons  per  second, 
i  second-foot  for  one  year  covers  i  square  mile  1.131  feet  or  13.572  inches 
deep. 

i  second-foot  for  one  year  equals  31,536,000  cubic  feet, 
i  second-foot  equals  about  i  acre-inch  per  hour, 
i  second-foot  for  one  day  covers  i  square  mile  0.03719  inch  deep, 
i  second-foot  for  one  28-day  month  covers  i  square  mile  1.041  inches  deep, 
i  second-foot  for  one  29-day  month  covers  i  square  mile  1.079  inches  deep, 
i  second-foot  for  one  3O-day  month  covers  i  square  mile  1.116  inches  deep, 
i  second-foot  for  one  3i-day  month  covers  i  square  mile  1.153  inches  deep, 
i  second-foot  for  one  day  equals  1.983  acre-feet, 
i  second-foot  for  one  28-day  month  equals  55.54  acre-feet, 
i  second-foot  for  one  29-day  month  equals  57.52  acre-feet, 
i  second-foot  for  one  30-day  month  equals  59.50  acre-feet, 
i  second-foot  for  one  31 -day  month  equals  61.49  acre-feet. 
100  California  miner's  inches  equal  18.7  United  States  gallons  per  second. 
100  California  miner's  inches  equal  96.0  Colorado  miner's  inches. 
100  California  miner's  inches  for  one  day  equal  4.96  acre-feet. 
100  Colorado  miner's  inches  equal  2.60  second-feet. 

100  Colorado  miner's  inches  equal  19.5  United  States  gallons  per  second. 
100  Colorado  miner's  inches  equal  104  California  miner's  inches. 
100  Colorado  miner's  inches  for  one  day  equal  5.17  acre-feet. 
100  United  States  gallons  per  minute  equal  0.223  second-foot. 
100  United  States  gallons  per  minute  for  one  day  equal  0.442  acre-foot. 
,000,000  United  States  gallons  per  day  equal  1.55  second-feet. 
,000,000  United  States  gallons  equal  3.07  acre-feet. 
,000,000  cubic  feet  equal  22.95  acre-feet. 

acre-foot  equals  325,850  gallons. 

inch  deep  on  i  square  mile  equals  2,323,200  cubic  feet. 

inch  deep  on  i  square  mile  equals  0.0737  second-foot  per  year. 

foot  equals  0.3048  meter. 

mile  equals  1.60935  kilometers. 

mile  equals  5,280  feet. 

acre  equals  0.4047  hectare. 

acre  equals  43,560  square  feet. 

acre  equals  209  feet  square,  nearly. 

square  mile  equals  2.59  square  kilometers. 

cubic  foot  equals  0.0283  cubic  meter. 

cubic  foot  equals  7.48  gallons. 

cubic  foot  of  water  weighs  62.5  pounds. 

cubic  meter  per  minute  equals  0.5886  second-foot. 

horsepower  equals  550  foot-pounds  per  second. 

horsepower  equals  76.0  kilogram-meters  per  second. 

horsepower  equals  746  watts. 

horsepower  equals  i  second-foot  falling  8.80  feet, 
if  horsepower  equal  about  i  kilowatt. 

Sec.-ft.  X  fall  in  feet 
To  calculate  water  power  quickly :  -        —  =  net  horsepower  on 

water  wheel,  realizing  80  per  cent  of  theoretical  power. 

4 


50  QUANTITY   OF   WATER   REQUIRED 

59.  Measurement  of  Water  Duty. — The  duty  of  water  may 
be  variously  expressed :  a,  by  the  number  of  acres  of  land  which 
a  second-foot  of  water  will  irrigate;  b,  by  the  number  of  acre- 
feet  of  water  required  to  irrigate  an  acre  of  land;  c,  in  terms 
of  the  total  volume  of  water  used  during  the  season;  or  d,  in 
terms  of  the  expenditure  of  water  per  linear  mile  of  canal.  The 
duty  of  water  varies  primarily  with  the  crop;  thus  rice  requires 
more  than  wheat.  It  varies  still  more  largely  with  the  soil,  since 
sandy  requires  far  more  than  clayey  soil.  It  varies  with  the 
temperature,  the  precipitation,  and  with  the  condition  of  the 
ditches,  since  flat,  shallow  channels  give  smaller  duties  than 
steeper  and  deeper  ones.  Above  all,  it  varies  with  the  skill  of 
the  irrigator. 

In  considering  the  duty  of  water  care  should  be  taken  to 
show  whether  it  is  reckoned  on  the  quantity  of  water  entering 
the  head  of  the  canal  or  the  quantity  applied  to  the  land,  since 
the  losses  by  seepage,  evaporation,  etc.,  in  the  passage  of  water 
through  the  canal  are  considerable.  Thus,  if  in  a  long  line  of 
canal  the  duty  is  estimated  at  150  acres  per  second-foot,  and 
the  losses  by  seepage  and  evaporation  are  33^  per  cent,  the 
duty  would  be  reduced  to  100  acres  at  the  point  of  application. 
Careful  measurements  made  on  various  canals  in  India  show 
the  loss  of  water  between  their  heads  and  the  heads  of  the  dis- 
tributaries to  vary  from  20  to  40  per  cent.  Where  duty  on  dis- 
charge at  canal  head  was  53  acres,  that  on  its  discharge  utilized 
was  72  acres;  while  the  duty  of  the  distributaries  on  their  dis- 
charge at  outlet  was  104  acres  per  second-foot. 

In  a  number  of  experiments  conducted  in  the  West  to  de- 
termine losses  in  canals  it  was  found  that  while  the  duty  at  the 
fields  varied  from  1.5  to  2.8  acre-feet  of  water  to  each  acre  irri- 
gated the  amount  of  water  used  based  on  measurements  at  the 
canal  head  amounted  to  from  3.8  to  6.6  acre-feet  per  acre.  In 
most  of  these  experiments  it  was  found  that  about  50  per  cent 
of  the  water  entering  the  canal  head  was  lost  by  absorption  and 
evaporation  before  it  reached  the  fields.  On  the  other  hand, 
these  losses  on  the  Gage  canal,  California,  which  is  cement  lined, 
amounted  to  only  6  per  cent. 


DUTY   PER    SECOND-FOOT 


60.  Duty  per  Second-foot. — The  duty  of  water  in  various 
portions  of  the  West  is  a  matter  of  extreme  doubt.  As  recently 
as  in  1883  it  was  estimated  in  Colorado  to  be  from  50  to  55  acres 
per  second-foot.  In  Montana  and  portions  of  Colorado  the 
farmers  still  state  the  duty  as  being  one  miner's  inch  to  the  acre, 
or  38.4  acres  per  second-foot.  Recent  experiments  show  that 
the  duty  is  rapidly  rising,  for  as  land  is  irrigated  through  a  series 
of  years  it  becomes  more  saturated,  and  as  the  subsurface  water- 
plane  rises  the  amount  of  water  necessary  to  the  production 
of  crops  is  diminished.  The  cultivation  of  the  soil  causes  it  to 
require  less  water.  The  adoption  of  more  careful  methods  in 
designing  and  constructing  distributaries  and  care  and  experience 
in  handling  water  increase  its  duty.  The  State  Engineer  of 
Colorado  now  accepts  100  acres  per  second-foot  as  the  duty  for 
that  State,  varying  on  the  supply  at  the  head  from  70  to  190  acres. 
In  Utah,  70  to  300  acres  per  second-foot  is  the  duty.  In  Montana 
it  is  about  80  acres  per  second-foot. 

In  the  following  table  the  duty  of  water  is  given  for  a  few 
foreign  countries  and  for  various  portions  of  the  West.  These 
duties  cannot  be  taken  as  fixed.  They  are  apt  to  be  increased 
with  experience,  and  in  the  same  State  or  even  in  the  same  neigh- 
borhood they  will  differ  according  as  the  crops,  soil,  altitude, 
and  the  skill  in  handling  the  water  vary. 

TABLE  VIII. 

DUTY   OF   WATER. 

(Based  on  Supply  entering  Canal  Head.) 


Locality. 

Duty  per 
Second  -foot 
in  Acres. 

Duty 
Acre-feet 
per  Acre. 

Northern  India 

no—  i  co 

Italy 

6c—  70 

Colorado 

80—  i  20 

4Q 

Utah.  . 

60—120 

6  7 

Montana  

80—100 

**-o 

4-7 

Wyoming  

7O  —  3O 

•J 
52 

Idaho  

60-80 

51 

New  Mexico  

60-80 

c  6 

Southern  Arizona  

lOO—ICO 

i  8 

San  Toaquin  Valley,  Cal  

100—150 

34 

Southern  California,  surface  irrigation  

ICO—  3OO 

2    2 

"          sub-irrigation  

300—  coo 

52  QUANTITY   OF   WATER   REQUIRED 

The  above  figures  are  for  duty  on  supply  entering  canal 
head.  The  duty  on  the  supply  utilized  will  average  20  to  40 
per  cent  greater.  The  reason  for  the  high  duty  given  for  such 
an  arid  region  as  Southern  California  is  because  the  water  there, 
being  valuable,  is  handled  with  great  care.  On  the  cement  lined 
canals  of  the  United  States  Reclamation  Service  in  Nevada, 
Arizona  and  elsewhere  the  duty  is  even  greater. 

61.  Duty  for  Various  Crops. — Where  great  care  was  taken 
on  an  experimental  farm  in  Wyoming  in  handling  water,  its  duty 
per  second-foot  was  found  to  be  as  high  as  94  acres  on  oats  and 
230  acres  on  potatoes.  In  Montana  a  duty  on  oats  of  150  acres 
per  second-foot  is  frequently  attained.  On  beets  in  California 
the  duty  is  often  250  to  300  acres,  in  Utah  200  acres,  and  in 
New  Mexico  100  acres.  In  Arizona  a  duty  of  50  acres  of  peaches 
per  second-foot  of  water  is  common  practice. 

At  the  Montana  experiment  station  Prof.  Samuel  Fortier 
found  the  following  duties  for  various  crops : 


Clover. 

Peas. 

Wheat. 

Barley. 

Oats. 

Depth  of  water  applied  

1  .02 

I.  IO 

1.  08 

.08 

1  .  34 

Number  of  applications  

2 

2 

2 

I 

2 

Average  head  of  water,  sec.  -ft  

I  .  c-2 

I  .  "?O 

i.7< 

4.04 

i  .  =50 

The  average  of  all  the  experiments  showed  1.2  acre-feet  of 
water  used  on  each  acre. 

62.  Depth  of  Water  required  to  Soak  Soil. — Recent  experi- 
ments conducted  under  the  direction  of  Prof.  L.  G.  Carpenter 
throw  valuable  light  on  the  depth  of  water  required  for  irrigation. 
It  may  be  generally  stated  that  the  experience  of  all  countries 
indicates  that  it  is  impossible  to  make  an  irrigation  with  a  depth 
of  less  than  3  inches  of  water  on  sod  ground  and  4  to  6  inches  on 
cultivated  crops,  though  under  certain  adverse  conditions  of 
soil  and  crop  as  much  as  10  inches  of  water  may  be  required. 
Experiments  conducted  in  India  have  shown  that  a  good  heavy 
rain  amounting  to  about  5  J  inches  soaks  into  the  earth  to  a  depth 
of  from  1 6  to  18  inches.  If  this  amount  of  water  were  applied 


QUANTITY   PER    SERVICE   AND   IRRIGATING    PERIOD       53 

three  times    in  the  season,  it  would  be   equivalent  to   a  total 
depth  of  i6J  inches  to  the  crop. 

63.  Quantity  per  Service  and  Irrigating  Period. — In  Colorado 
alfalfa  and  clover  are  irrigated  twice  in  a  season,  once  in  May 
and  once  in  June,  to  a  depth  of  6  inches  for  each  period ;  wheat 
and  oats  are  irrigated  twice,  once  in  June  and  once  in  July,  to  a 
depth  of  9  and  6  inches  respectively.     Meadow  or  native  hay 
requires  considerably  more  water;   there  are  usually  two  service 
periods,  each  of  which  lasts  several  days,  the  water  being  allowed 
to  run  in  a  small  quantity  during  that  time.     The  first  is  usually 
in  May,  and  is  about  two  inches  in  depth  for  a  week;  the  second 
in  July  or  August,  of  about  the  same  amount;   in  all  from  24  to 
30  inches  in  depth  of  water  are  applied.     Since  the  application  of 
water  is  generally  followed  by  a  temporary  checking  of  the  growth 
of  the  plant,  the  method  preferred  in  the  arid  region  seems  to  be 
to  give  thorough  rather  than  many  irrigations;  in  other  words,  to 
have  two  ample  rather  than  four  to  six  small  services.     In  general 
it  may  be  stated  that  two  or  three  service  periods  varying  in  depth 
from  3  to  6  inches  are  employed  in  Colorado,  and  that  the  irriga- 
tion  period   extends  from   May  to   September — 123   days.     In 
Utah  the  practice  seems  to  be  to  employ  a  much  larger  number  of 
service  periods, — from  three  to  five  on  grain  crops  of  2  to  3  inches 
in  depth  each, — the  water  running  12  to  15  hours  per  service 
period,  and  the  irrigation  period  extending  from  June  to  August 
inclusive.     On  vegetables  as  many  as  six  to  ten  service  periods 
are  employed,  each  lasting  from  3  to  6  hours  during  June  to 
August    inclusive.     The    irrigating    period    in    the    majority    of 
Western  States  averages  from  April  15  to  August  15,  or  about 
120  days;   while  the  service  period  varies  from  3  to  15  hours  in 
length  according  to  soil  and  crop,  and  there  are  from  two  to 
eight  such  service  periods  in  an  irrigating  period.     In  India  there 
are  from  three  to  five  service  periods,  making  up  an  irrigating 
period  of  from  100  to  130  days'  duration. 

64.  Duty  per  Acre-foot. — Assuming  an  average  depth  of  4 
inches  of  water  as  sufficient  to  soak  the  soil  thoroughly,  this 
is  equivalent  to  J  of  an  acre-foot  per  acre.     An  average  crop 
requires   from   two   to   four   waterings   per   season.     Assuming 


54  QUANTITY    OF   WATER   REQUIRED 

three  as  the  mean,  then  at  the  above  rate  one  acre-foot  will  be 
required  per  season  to  irrigate  an  acre.  Practice,  however, 
clearly  indicates  that  this  theoretic  amount  is  too  low.  Experi- 
ments conducted  in  Wyoming  indicate  that  12  inches  in  depth 
for  potatoes  to  24  inches  in  depth  for  oats  are  sufficient  to  mature 
crops.  In  Idaho  the  depth  of  water  generally  used  is  about 
24  inches,  while  in  Montana  from  15  to  18  inches  is  believed  to  be 
sufficient.  These  indicate  volumes  ranging  from  ij  acre-feet  in 
Montana  to  2  acre-feet  in  Wyoming  and  Idaho,  as  duties  estimated 
on  the  amount  of  water  entering  the  canal  heads.  Measurements 
on  several  canals  in  Colorado  show  that  from  1 8  to  24  inches  in 
depth  of  water  are  required,  or  from  ij  to  2  acre-feet  per  acre. 
Experiments  conducted  by  Mr.  Samuel  Fortier  in  Utah  indicate 
that  a  depth  of  24  inches  is  required  for  tomatoes,  while  potatoes 
yield  abundantly  with  a  depth  of  17  inches,  onions  with  a  depth 
of  36  inches,  strawberries  with  27  inches,  and  orchards  with  12 
inches.  A  recent  careful  measurement  of  water  duty  on  mixed 
crops  near  Yuma,  Arizona,  the  hottest  place  in  the  United  States, 
shows  a  duty  of  5  acre-feet  per  acre. 

65.  Linear  and  Areal  Duty. — Experiments  made  in  India 
show  that  from  6  to  8  second-feet  of  water  should  be  allowed  per 
linear  mile  of  canal,  depending  on  the  area  commanded  on  either 
side  of  the  canal.  On  the  Soane  canal  in  India  a  more  con- 
venient unit  was  employed,  it  having  been  discovered  that  about 
three-fourths  of  a  second-foot  was  sufficient  for  a  square  mile 
of  gross  area.  As  the  net  area  irrigated,  however,  is  rarely  more 
than  two-thirds  of  the  gross  area  commanded,  perhaps  about  one- 
half  a  second-foot  is  sufficient  to  irrigate  a  square  mile  with  the 
most  economic  use.  On  the  Reclamation  Service  projects  a 
more  liberal  allowance  is  provided.  On  the  Uncompahgre 
canal,  Colorado,  one  second-foot  at  the  headgates  is  allowed  for 
each  80  acres;  and  on  the  Interstate  canal,  Neb.-Wyo.,  ij 
second-feet  to  100  acres. 

In  estimating  the  duty  of  water  stored  in  a  reservoir  or  diverted 
from  a  stream,  allowance  must  be  made  for  the  losses  due  to 
evaporation  and  absorption  in  conducting  the  water  to  the  fields. 
As  this  averages  25  to  50  per  cent,  it  follows  that  where  a  duty  of 


PERCENTAGE   OF    WASTE    LAND 


55 


i  acre-foot  per  acre  is  possible  ij  to  i  J  acre-feet  must  be  provided 
at  the  headgates,  and  where  2  acre-feet  per  acre  is  the  duty  2\ 
acre-feet  must  be  provided.  In  estimating  the  total  duty  of  the 
supply  consideration  must  be  given  to  the  area  of  waste  land 
(Art.  66),  which  will  increase  the  duty  by  about  20  per  cent. 
On  the  Reclamation  Service  projects  liberal  allowances  of 
water  are  provided.  For  the  Salt  River  project,  in  a  very  arid 
region,  a  duty  of  4  acre-feet  is  allowed;  for  the  Yuma  canals,  in 
the  most  arid  region,  5.5  acre-feet;  for  the  Minidoka  canals, 
Idaho,  4  acre-feet;  and  for  the  Interstate  canals,  Nebraska,  2 
acre-feet. 

66.  Percentage  of  Waste  Land. — In  every  irrigated  area  but 
a  small  percentage  of   the  total  area   commanded   is   irrigated 
in  any  one  season.     Some  of  the  land  is  occupied  by  roads,  farm- 
houses, or  villages.     Some  is  occupied  by  pasture-lands,  which 
receive  sufficient  moisture  by  seepage  from  adjoining  irrigated 
fields;    and  some  by  barnyards,   while  occasionally  fields   are 
allowed  to  lie  idle  for  a  season.     It  has  been  observed  in  India 
that  but  two-thirds  to  four-fifths  of  the  total  area  commanded 
are  irrigated.     On  the  Soane  canal  in  India,  about  500  acres  out 
of  every  640  are  irrigated.     From  estimates  made  in  well  irri- 
gated portions  of  the  West  it  appears  that  if  water  is  provided  for 
500  out  of  every  640  acres,  it  will  be  sufficient  to  supply  all  the 
demands  of  the  cultivators.     Keeping  this  in  mind,  it  will  be 
seen  that  the  actual  duty  of  water  entering  the  canal  head,  when 
estimated  on  large  areas,  is  at  least  20  per  cent  greater  than  the 
theoretic  duty  per  acre. 

67.  Tatils,  or  Rotation  in  Water  Distribution. — The  water 
in  distributaries  can  be  most  economically  handled  if  a  system 
of  rotation  be  employed  in  admitting  it  to  the  heads  of  the  private 
channels.     It  is  more  convenient  and  economical  to  use  water 
in  as  large  heads  and  volumes  as  possible;   in  fact,  the  volumes 
of  water  flowing  in  many  small  distributaries  are  so  small  that, 
if  irrigation  were  b,eing  practised  all  along  its  line  at  the  same 
time,  sufficient  would  not  reach  the  lower  end  of  the  distributary 
to  moisten  its  bed,  much  less  flow  over  the  fields.     It  is  therefore 
essential  in  such  cases  to  divide  the  distributary  into  a  number 


56  QUANTITY   OF   WATER   REQUIRED 

of  sections,  in  each  of  which  the  water  is  permitted  to  flow  with 
full  head  for  a  given  period,  and  the  irrigators  are  compelled  to 
use  the  water  at  the  time  when  it  is  available  in  their  section, 
be  it  night  or  day. 

This  system  of  irrigating  by  rotation,  or  by  "tatils"  as  it 
is  called  in  India,  is  of  great  advantage  not  only  in  checking 
the  loss  of  water  in  the  channels  and  giving  sufficient  head  to 
each  irrigator  to  flow  his  land,  but  also  in  teaching  economical 
irrigation  to  the  cultivators  and  insuring  a  fair  division  of  water 
among  them.  Thus  an  irrigator  who  is  entitled  to  but  J  second- 
foot  of  water  during  an  irrigating  period  of  100  days  would  find 
that  volume  too  small  to  be  economically  and  practically  handled; 
but  if  he  were  permitted  to  use  4  second-feet  during  12  days, 
divided  into  three  tatils  or  service  periods  of  four  days  each,  he 
would  be  able  to  make  a  satisfactory  and  economical  use  of  such 
a  head. 

These  tatils  are  imposed  by  regulating  the  amount  admitted 
to  the  private  channels  and  the  period  of  time  in  which  it  shall 
enter  them.  The  outlets  of  these  channels  may  be  closed  in  the 
first  section  of  the  canal  for,  say,  4  days ;  in  the  second  for  3  days ; 
and  this  order  may  be  reversed,  the  period  of  rotation  being 
such  as  to  vary  and  equalize  the  period  of  closure  among  the 
several  sections.  It  is  better  to  impose  these  systems  of  rotation 
on  long  portions  of  the  distributaries  at  the  same  time,  since  the 
effect  of  forcing  water  down  to  the  tail  of  the  distributaries  is 
then  more  noticeable.  Thus,  if  the  canal  be  twenty  miles  in 
length  and  all  the  outlets  in  the  first  five  miles  be  closed,  those  in 
the  second  five  miles  opened,  those  in  the  third  five  miles  closed, 
and  those  in  the  fourth  five  miles  opened  all  at  the  same  time, 
the  effect  will  be  to  produce  a  stronger  head  and  carry  the  desired 
amount  to  all  the  channels  in  the  last  portion  of  the  canal;  then 
for  a  few  days  this  order  may  be  reversed,  and  the  maximum  duty 
obtained  in  the  remaining  portions  of  the  distributaries  with- 
out difficulty.  To  make  such  a  system  effective,  rules  must 
be  enforced  compelling  irrigators  to  accept  water  when  their 
irrigating  heads  are  open  and  refusing  it  to  them  when  their 
turn  has  gone  by. 


WORKS    OF   REFERENCE  57 

68.  Works  of  Reference.     Duty  of  Water. 

BERESFORD,  J.  S.  Duty  of  Water  and  Memoranda  on  Irrigation.  Professional 
Papers,  Second  Series,  No.  212.  Roorkee,  India. 

BUCKLEY  R.  B.  Irrigation  Works  in  India  and  Egypt.  E.  &  F.  N.  Spon.  Lon- 
don, 1894. 

CARPENTER,  L.  G.  Third  Annual  Report  on  Meterorology  and  Engineering  Con- 
struction, State  Agricultural  College  of  Colorado,  1890.  Fort  Collins,  Colorado. 
— Duty  of  Water.  Bulletin  22,  State  Agricultural  College.  Fort  Collins, 
Col.,  1893. 

DEAKIN,  ALFRED.  Royal  Commission  on  Water  Supply.  First  and  Fourth 
Progress  Reports,  Irrigation  in  Western  America,  Egypt,  and  Italy.  Mel- 
bourne, 1885. 

FLYNN,  P.  J.     Irrigation  Canals  and  other  Irrigation  Works.     Denver,  Colo.,  1892. 

FOOTE,  A.  D.     Report  on  Irrigation  of  Desert  Lands  in  Idaho.     New  York,  1887. 

FORTIER,  SAMUEL.  Water  for  Irrigation.  Bulletin  26,  Utah  Agricultural  Col- 
lege. Logan,  Utah,  1893. 

HALL,  WILLIAM  HAM.  Report  of  the  State  Engineer  to  Legislature  of  California. 
Sacramento,  1880. 

KING,  F.  H.     Irrigation  and  Drainage.     The  Macmillan  Co.     New  York,  1899. 

MEAD,  ELWOOD;  FORTIER,  SAMUEL;  and  others.  Use  and  Duty  of  Water  in 
Irrigation.  Bulletin  86,  Office  of  Experiment  Station,  Dept.  of  Agriculture, 
Washington,  D.  C. 

NEWELL,  F.  H.  Agriculture  by  Irrigation.  Report  of  the  nth  Census,  1890. 
Washington,  D.  C.,  1894. 

WILSON,  HERBERT  M.  Irrigation  in  India.  Part  II,  i2th  Annual  Report  of  the 
U.  S.  Geological  Survey.  Washington,  D.  C.,  1891. 

American  Irrigation  Engineering.     Part  II,   i3th  Annual  Report  of  the 

U.  S.  Geological  Survey.     Washington,  D.  C.,  1892. 

United  States  Reclamation  Service,  Annual  Reports.     Government  Print- 
ing Office,  Washington,  D.  C. 


CHAPTER  VI 

FLOW  AND   MEASUREMENT   OF   WATER  IN   OPEN    CHANNELS 

69.  Physical  and  Chemical  Properties  of  Water. — Water  is 
composed  of  an  infinite  number  of  minute  particles,   each  of 
which  has  weight  and  can  receive  and  transmit  this  in  the  form 
of  pressure  in  all  directions.     The  particles  composing  water 
move  upon  and  among  each  other  with  an  inappreciable  amount 
of  friction.     Water  is  composed  of  at  least  two  atomic  substances, 
oxygen  and  hydrogen,  combined  in  the  ratio  of  one  of  oxygen  to 
two  of  hydrogen,  the  whole  forming  a  molecule  of  water.     These 
molecules  are  so  fine  that  it  has  been  estimated  that  there  are 
from  500  to  5000  in  a  linear  inch. 

70.  Weight  of  Water. — Water  reaches  its  maximum  density 
at  about  39.2°  Fahrenheit,  and  the  weight  of  a  cubic  foot  of  dis- 
tilled water  at  this  temperature  is  62.425  pounds;  and  of  a  U.  S. 
gallon  8.3799  pounds.     Below  and  above  this  temperature  the 
weight  of  a  given  volume  of  water  decreases.     The  weight  of  a 
cubic  foot  of  ice  is  57.2  pounds.     At  32°  Fahrenheit  a  cubic  foot 
of  distilled  water  weighs  62.417  pounds,  and  its  weight  increases 
from  this  to  the  maximum  density  above  given,  from  which  it 
decreases  to  62.367  pounds  at  60°  Fahrenheit,  and  continues  to 
decrease  almost  uniformly  to  a  weight  of  59.837  pounds  at  a 
temperature  of  212°,  which  is  the  boiling  point  of  water.     Ordi- 
nary pond,  brook,  or  spring  water  is  heavier  than  distilled  water 
because  of  the  trifling  amounts  of  salts  carried  in  solution  in  most 
fresh  waters;   while  salt  water  or  water  laden  with  sediment  is 
still  heavier,  according  to  the  amount  of  soluble  or  suspended 
matter  in  a  given  volume. 

71.  Pressure  of  Water. — Each   molecule  of  water  is  inde- 
pendently subject  to  the  force  of  gravity,  and  therefore  has  weight. 
When  water  is  pressed  by  its  own  weight  or  that  of  any  other 
force,  this  pressure  is  transmitted  equally  in  all  directions.     The 

58 


AMOUNT   OF   PRESSURE   OF   WATER  59 

pressure  at  any  point  of  a  volume  of  water  is  in  proportion  to 
the  vertical  depth  of  that  point  below  the  surface,  and  is  in- 
dependent of  the  breadth  of  the  volume  of  water.  If  water 
be  contained  in  a  vessel  of  any  form  in  which  an  orifice  is  made 
the  particles  of  water  at  that  point  are  relieved  of  the  resistance 
of  the  confining  surface,  and  at  once  slide  on  each  other  and 
flow  out  of  the  orifice  with  a  velocity  proportional  to  its  depth 
below  the  surface,  or  to  what  is  known  as  the  "head."  The 
pressure  due  to  a  column  of  water  in  a  vertical  tube  is  directly 
proportional  to  its  height,  and  if  the  column  be  bent  or  inclined 
at  any  angle  the  pressure  will  not  be  dependent  on  the  length 
of  the  crooked  confining  channel,  but  on  the  height  of  the  surface 
vertically  above  the  lowest  part  of  the  column. 

72.  Amount  of  Pressure  of  Water. — A  cubic  foot  of  water 
is  ordinarily  taken  as  weighing  62.5  pounds,  and  the  pressure  per 
square  inch  for  each  vertical  foot  of  depth  below  the  surface 
of  water  is  about  0.434  pound.     By  means  of  the  ordinary  methods 
adopted  in  considering  the  parallelogram  of  forces,  the  pressure 
of  a  body  of  water  against  an  inclined  surface  at  any  given  point 
may  be  determined  by  representing  the  depth   (or  the  weight 
due  to  the  depth  at  that  point)  by  a  line,  the  length  of  which 
bears  a  certain  proportion  to  the  weight,  and  by  resolving  this 
inclined  line  into  its  resultant  horizontal  and  vertical  components, 
these  latter  will  then  represent  the  relative  horizontal  and  vertical 
pressures  exerted  by  the  water  against   that   point.     To  find 
the  total  pressure  of  water  on  any  surface  its  area  in  square  feet 
should  be  multiplied  by  the  vertical  depth  of  its  centre  of  gravity 
below  the  water  surface  in  feet,  and  the  total  by  the  weight  of 
one  cubic  foot  of  water. 

Making  h  =  ihe  head  or  depth  below  the  surface,  />  =  the 
pressure  in  pounds  at  that  point,  and  g  the  depth  of  the  centre 
of  gravity  of  the  mass  of  water  below  the  surface,  or  one-half 
of  h,  and  the  weight  of  a  cubic  foot  of  water  being  62.5  pounds, 
we  have  p  =  62.$h. 

73.  Centre  of   Pressure. — The  force  which   tends   to   over- 
turn or  push  a  surface  about  a  given  point  is  not  in  the  centre 
of  gravity  of  the  body  of  water,  but  at  two-thirds  of  the  depth 


60         FLOW   AND   MEASUREMENT   IN   OPEN   CHANNELS 

from  the  surface  to  that  point,  and  is  known  as  the  centre  of 
hydrostatic  pressure,  while  the  j^nire  of  gravity  is  at  one-half 
the  vertical  depth  of  the  point.  The  total  pressure  upon  a  curved 
surface  is  proportional  to  the  total  length  of  that  surface,  but 
the  horizontal  effect  of  this  pressure  is  directly  proportional  to 
the  vertical  projection  of  the  surface. 

74.  Atmospheric  Pressure. — The  weight  of  the  atmosphere 
upon  the  surface  of  any  substance  at  the  level  of  the  sea  is  about 
14.75  pounds  per  square  inch.     This  quantity  is  known  as  an 
atmosphere,  and  will  sustain  a  column  of  water  34.028  feet  in 
height.     In  other  words,  the  pressure  of  the  atmosphere  would 
raise  a  column  of  water  to  this  height.     It  is  on  this  account 
that  it  is  possible  to  raise  water  by  pumping  or  to  cause  water 
to  flow  through  a  siphon.     The  act  of  pumping  or  of  raising 
water  by  a  siphon  produces  a  vacuum  above  the  water,  and 
the  pressure  of  the  atmosphere  forces  the  water  up  to  fill  this 
vacuum  to  a  height,  approximately,  of  34  feet  at  sea  level.     Ow- 
ing, however,  to  friction  and  other  causes,  water  can  never  be 
raised  to  quite  this  height ;  while  at  altitudes  above  the  sea  level 
where  the  atmosphere  is  lighter,  its  sustaining  power  is  diminished 
and  the  height  to  which  it  will  force  water  is  diminished  propor- 
tionately. 

75.  Motion  of  Water. — The  motion  of  water  is  due  to  a 
destruction  of  the  equilibrium  among  the  particles  forming  its 
mass,  and  it  is  said  to  "flow"  because  the  action  of  gravity  gen- 
erates motion  and  destroys  equilibrium.     The  motion  of  a  falling 
body  is  constantly  accelerated  by  the  force  of  gravity  in  regular 
mathematical  proportion.     At  the  level  of  the  sea  a  body  falling 
freely  in  vacuo  drops  a  height  of  16.1  feet  during  the  first  second 
of  time,  its  velocity  at  the  end  of  the  first  second  being  32.2  feet, 
and  it  is  accelerated  by  this  amount  for  each  succeeding  second. 
It  is  this  quantity  which  is  known  as  the  acceleration  of  gravity, 
and  which  is  usually  designated  by  the  letter  g  in  hydraulic  for- 
mulas.    The  velocity  v  of  a  body  at  the  end  of  a  given  space  of 
time  /  is  equal  to  the  product  of  time  into  its  acceleration  by 
gravity.     Thus,  v  =  gt.     It  has  been  shown  that  the  height  h, 
through  which  the  body  falls  or  through  which  its  pressure  is 


FACTORS'  AFFECTING    FLOW  6l 

accelerated,  is  equal  to  one-half  of  the  gravity,  and  the  heights 
fallen  in  any  given  time  are  as  the  squares  of  the  time;    hence 

_£_,  and  substituting,  transposing,  and  eliminating,  we  have 


76.  Factors  affecting  Flow.  —  If  an  open  channel  be  given 
the  smallest  possible  inclination  in  one  direction,  the  water  con- 
tained therein  will  be  at  once  set  in  motion  by  the  act  of  gravity, 
and  its  particles  will  fall  one  over  the  other  in  the  direction  of 
the  inclination  until  motion  or  flow  in  that  direction  takes  place. 
The  effect  of  the  action  of  gravity  to  produce  motion  is  dependent 
on  the  slope,  and  this  is  usually  represented  by  the  ratio  of  the 
vertical  to  the  horizontal  distance;  so  we  have  as  factors  repre- 
senting the  velocity  of  flow  the  length  of  the  channel,  /,  for  a 
vertical  fall  of  any  given  height,  //.  The  amount  of  friction 
offered  by  the  sides  of  the  channel  to  the  flow  of  water  and  tending 
to  impede  its  velocity  is  one  of  the  important  factors,  and  is  de- 
pendent chiefly  on  the  nature  of  the  bed  and  sides  of  the  channel, 
that  is,  to  the  lining  or  surface  of  the  channel  against  which  the 
water  flows,  and  on  the  length  of  wetted  perimeter  or  the  sectional 
area  against  which  the  water  presses.  Other  quantities  on 
which  the  coefficients  of  flow  in  channels  depend  are  the  hydraulic 
mean  depth,  r,  which  is  equal  to  the  area  of  the  cross-section 
of  the  water  in  square  feet,  A,  divided  by  the  wetted  perimeter 
in  linear  feet,  p.  A  simple  formula  representing  the  mean  velo- 
city of  flow  is 


......  (7) 

m 

in  which  i  is  the  sine  of  the  inclination  h  divided  by  /  in  feet; 
h  being  the  fall  of  the  water  surface  in  the  distance  /;  m  is  a 
variable  coefficient,  which  includes  most  of  the  minor  modifying 
factors.  The  value  of  m  varies  between  .05  for  a  hydraulic  mean 
radius  of  .25,  to  .0298  for  a  hydraulic  mean  radius  of  i,  and 
diminishes  constantly  thence  to  a  value  of  .0074  for  a  hydraulic 
mean  radius  of  10  and  .002  for  a  hydraulic  mean  radius  of  25. 
77.  Formulas  of  Flow  in  Open  Channels.  —  The  formulas  for 


62          FLOW   AND    MEASUREMENT    IN    OPEN    CHANNELS 

finding  the  mean  velocity  of  flow  in  open  channels  have  all  con- 
stant coefficients,  and  are  therefore  incorrect  outside  of  a  small 
range  of  dimensions.  As  a  result  of  experiments  on  the  Missis- 
sippi by  Humphreys  and  Abbot,  and  of  experiments  made  in 
India,  Kutter  has  devised  a  formula  which  takes  into  account  the 
resistance  due  to  the  varying  quantities  n  and  k,  which  depend  on 
the  nature  of  the  surface  of  the  channel.  Bazin  made  some  ex- 
periments on  small  canals,  from  which  he  devised  a  formula 
which  has  been  received  with  popular  favor.  This  formula  is 
arranged  with  various  constant  factors,  according  to  the  four 
grades  of  roughness  of  the  surface  of  the  channel.  Modifications 
of  this  formula  have  been  devised  by  D'Arcy  which  are  still  more 
convenient  to  use.  D'Arcy's  formula  is 

I  10002  /«\ 

•v  =  r\  -  —  >  W 

V  .08534  •+  0.35 

in  which  i  equals  the  fall  of  water  in  any  distance,  /  divided  by 
that  distance  =  —  =  the  sine  of  the  slope. 

78.  Kutter Js  Formula. — The  formula  which  is  now  most 
approved  for  determining  the  velocities  of  flow  in  open  channels 
is  Kutter's  formula, 


1.811   ,        ,  ,  .00281 

-  +  4I.6+ — 


.00281 


MX  n- 

i      )      Vr 


(9) 


Substituting  for  the  first  term  of  the  right-hand  factor  the  letter  C, 
we  have  Chazy's  formula 

v=CVri=CV~rX\/T.      .     .     .     (10) 

For  small  channels  of  less  than  20  feet  bed  width  Bazin 's 
formula  gives  fair  results  where  the  sides  and  bottom  are  well 
built.  The  coefficients  in  this  formula  depend  on  the  nature  of 
the  surface  of  the  material  and  the  hydraulic  mean  depth.  The 
following  table,  from  Flynn's  "Flow  of  Water  in  Open  Channels," 
gives  the  value  of  C  for  a  wide  range  of  earth  channels,  and  will 
cover  nearly  everything  occurring  in  ordinary  practice. 


KUTTER'S    FORMULA  63 

TABLE  IX. 

VALUE  OF  V  IN  FEET  PER  SECOND  AND  OF  C  FOR    EARTH    CHAN- 
NELS, BY  KUTTER'S  FORMULA. 


n  =  .0225 

\/~r  in  feet. 

r  in. 

0.7 

I  .0 

1.8 

2-5 

4.0 

V 

C 

V 

C 

V 

C 

•v 

C 

V 

C 

1000 

1.17 

5i-5 

2.01 

62.5 

4.88 

80.3 

7.08 

89.2 

I2-73 

99-9 

i2«;o 

1.04 

5i-3 

i-79 

62.3 

4.17 

80.3 

6.38 

89-3 

"-43 

IOO.2 

1667 

.85 

51.0 

i-54 

62.1 

3-58 

80.3 

5-54 

89-  5 

9-95 

100.6 

2500 

.72 

50-4 

1.25 

61.7 

2-95 

80.3 

4-54 

89.8 

8.19 

101.4 

3333 

.62 

49-8 

1.07 

61.2 

2-54 

80.2 

3-94 

90.1 

7.14 

102.3 

5000 

-50 

48.9 

-87 

60.5 

2.05 

80.3 

3-24 

90.7 

5-92 

103-7 

7500 

.42 

47-5 

-73 

59-4 

i-77 

80.3 

2.78 

9i-5 

5-'3 

106.0 

IOOOO 

-34 

46.4 

.60 

58-5 

1.49 

80.3 

2-33 

92.3 

4-55 

107.9 

2OOOO 

.22 

43  -° 

.40 

55-7 

1.20 

80.2 

1.70 

94-8 

3-29 

115.0 

n  =  .035 

\/~r  in  feet. 

0.7 

I.O 

1.8 

2-5 

4-0 

V 

C 

V 

C 

V 

C 

V 

C 

V 

C 

1000 

0.67 

29.9 

1.19 

37-6 

2.85 

51-6 

4.69 

59-3 

8.76 

69.2 

1250 

.60 

29.8 

1.  06 

37-6 

2-51 

51.6 

4.20 

59-4 

9.86 

69.4 

1667 

-57 

29.6 

.92 

37-4 

2.40 

51.6 

3-62 

59-5 

6.84 

69.8 

2500 

.42 

29.2 

-74 

37-1 

1.85 

51-6 

3-oo 

59-7 

5-63 

70.4 

3333 

-36 

28.9 

.64 

36-9 

1.  60 

51-6 

2.60 

59-9 

4.92 

71.0 

5000 

.29 

28.3 

•51 

36-4 

1.30 

51-6 

2.IO 

60.4 

4.08 

72.2 

7500 

.24 

27.7 

.42 

35-8 

I.  II 

51-6 

I.  80 

60.9 

3-55 

73-9 

IOOOO 

.19 

27.1 

-35 

35-3 

-93 

51-6 

1.50 

60.5 

3.02 

75-4 

20000 

-r3 

25-4 

.24 

33-8 

-65 

51-5 

I.IO 

63-1 

2.28 

80.6 

This  table  is  arranged  with  two  different  values  for  the  factor 
n  which  are  dependent  on  different  qualities  of  surface  in  the 
channel.  The  accuracy  of  Kutter's  formula  depends  chiefly  on 
the  selection  of  the  coefficient  of  roughness  n,  and  experience  is 
required  in  order  to  give  the  right  value  to  this  coefficient.  In 
order  to  provide  for  the  future  deterioration  of  the  channel  surface 
by  the  growth  of  weeds  or  its  abrasion,  it  is  well  to  select  a  high 
value  for  n.  The  following  are  some  of  the  values  of  n  for  dif- 


64          FLOW   AND   MEASUREMENT   IN    OPEN   CHANNELS 

ferent  materials  as  derived  from  Jackson,  Hering,  Kutter,  and 

others : 

n  =  .009  for  well-planed  timber; 

n  =  .oi  for  plaster  in  cement,  glazed  iron  pipes,  and  glazed  stone- 
ware pipes ; 

n  =  .oi2  for  wooden  pipe,  rough  plank  flumes,  concrete,  and  re- 
inforced concrete; 

^  =  .013  to  .017  for  ashlar  masonry,  tuberculated  iron  pipes,  and 
brickwork  according  to  the  smoothness  of  the  surface  and 
its  condition;  about  .014  for  good  ashlar  or  brick  and  .018 
for  rubble  masonry; 

n  =  .oi6  for  riveted  steel  conduits; 

n=.o2  for  rubble  in  cement  and  coarse  rubble  of  nearly  all  kinds; 
also  for  coarse  gravel  carefully  laid  and  rammed,  or  for 
rough  rubble  where  the  interstices  have  become  filled  with 
silt; 

^  =  .0225  in  good  earth  canals; 

w  =  .o25  to  .03  in  canals  from  those  having  tolerably  uniform 
cross-section  and  slopes  to  those  which  are  in  rather  bad 
order,  and  have  some  stones  and  weeds  obstructing  the 
channels ; 

^  =  .035  to  -°5  from  canals  and  rivers  with  earth  beds  in  bad 

order  and  obstructed  by  stones,  etc.,  to  torrents  covered 

with  all  varieties  of  detritus,  and  overflowed  tree-covered 

banks. 

As  an  indication  of  the  extent  to  which  the  value  of  n  affects 

the  velocity  of  the  discharge  of  channels,  let  us  take  an  example 

in  which  n  =  0.02  2  5.     A  bed  width  of  10  feet,  depth  of  2  feet,  and 

side  slopes  of  i  to  i,  with  a  grade  of  8  feet  per  mile,  gives  a  velocity 

of  3.32  feet  per  second  and  a  discharge  of  79.07  second-feet. 

For  the  same  channel  with  a  value  of  ^  =  .035  the  velocity  is  2.05 

feet  per  second  and  the  discharge  49.2  second-feet;  thus  showing 

that  with  the  better  channel  the  discharge  is  60  per  cent  greater 

than  with  the  inferior  channel. 

79.  Tables  for  Use  with  Kutter's  Formula. — Tables   X  to 

XIV  inclusive  are  in  large  part  derived  by  condensation  from 

Flynn's  tables,  and  greatly  facilitate  the  various  computations 


DISCHARGE   OF    STREAMS    AND   VELOCITIES 


of  flow  in  open  channels,  in  connection  with  Chazy's  adaptation 
of  Kutter's  formulas  v  =  C\/ri  and  Q  =  Av. 

Table  X  gives  the  sine  of  the  inclination  i '  =  —  in  feet,  and  also 

\/ i  for  given  grades  and  slopes  from  one-fourth  of  a  foot  per 
mile  to  thirty  feet  per  mile.  Tables  XI,  XII,  and  XIII  give, 
respectively,  the  area  A  in  square  feet,  the  hydraulic  mean  depth 
r  in  feet,  and  the  \/r  for  rectangular  channels,  and  also  for  trape- 

TABLE  X. 

GRADES,  SLOPES,  AND  VALUES  OF  i  AND  \/T  FOR  USE  IN 
KUTTER'S  FORMULA  v 


Grade 
in  Feet 
per  Mile. 

Slope  i  in 

i 

VT 

Grade 
in  Feet 
per  Mile. 

Slope  i  in 

1 

v~r 

-25 

2II2O 

.000047 

.0069 

10 

528 

.001894 

-0435 

•50 

10.560 

.000094 

.0097 

II 

444 

.002083 

.0456 

•75 

7040 

.000142 

.0119 

12 

440 

.002273 

.0477 

i 

5280 

.000189 

-OI37 

13 

406 

.002462 

.0496 

!-25 

4224 

.000236 

.0154 

14 

377 

.002651 

-0515 

i-5 

3520 

.000284 

.0168 

15 

352 

.002841 

-0533 

i-75 

3OI7 

-000331 

.0182 

16 

330 

.003030 

-0550 

2 

2640 

.000378 

.0194 

'7 

311 

.003219 

.0567 

2-25 

2-347 

.000426 

.0206 

18 

293 

.003409 

.0584 

2-5 

2112 

.000473 

.0217 

19 

278 

.003598 

-0599 

2-75 

IQ20 

.000521 

.0228 

20 

264 

.003788 

.0615 

3 

1760 

.000568 

-0238 

21 

251 

.003977 

.0630 

3-25 

1625 

.000615 

.0248 

22 

240 

.004166 

.0645 

3-5 

1508 

.000663 

.0257 

23 

229 

.004356 

.0660 

3-75 

1408 

.000710 

.0266 

24 

220 

-004545 

.0674 

4 

1320 

.000757 

.0275 

25 

211 

-004735 

.0688 

5 

1056 

.000947 

.0307 

26 

203 

.004924 

.0702 

6 

880 

.001136 

-°337 

27 

195 

-005113 

-0715 

7 

754-3 

.001325 

.0364 

28 

188 

-005303 

.0728 

8 

660 

.001515 

.0389 

29 

182 

.005492 

.0741 

9 

586.6 

.001704 

.0413 

3° 

176 

.005682 

-0754 

zoidal  channels  having  side  slopes  of  i  on  i  and  i  on  ij,  corre- 
sponding to  depths  of  from  i  to  10  feet  and  bed  widths  of  from  3 
to  100  feet.  Table  XIV  gives  the  coefficients  of  roughness  C 
for  different  values  of  n  and  for  values  of  r  from  o.i  to  10,  and  of  i, 
from  .0001  to  .01. 

80.  Discharge    of    Streams    and    Velocities    of    Flow. — The 
quantity  of  discharge  of  a  canal  or  river,  Q,  in  second-feet  is 
obtained  by  multiplying  its  velocity,  v,  in  feet  per  second  into 
5 


66 


FLOW   AND   MEASUREMENT   IN    OPEN   CHANNELS 


the  cross-sectional  area,  A,  of  the  channel  in  square  feet.  Alge- 
braically expressed, 

Q=Av, (11) 

or,  substituting  for  v  its  value  from  equation  (10), 

Q=CXAx\/rXVT, (12) 

Since  the  discharge  of  an  open  channel  depends  primarily  on 
a  knowledge  of  its  mean  velocity,  it  will  be  well  to  consider  the 
relation  of  this  to  the  velocities  in  other  portions  of  the  channel. 
In  any  open  channel  the  film  of  water  in  contact  with  the  open 
air  has  a  velocity  which  is  a  trifle  slower  than  that  in  the  centre 

TABLE  XI. 

VALUES   OF   A    IN   SQUARE    FEET,    r   IN    FEET,    AND    \/r    FOR 
CHANNELS   HAVING    VERTICAL    SIDES. 

For  Use  in  Kutter's  Formula  v  =  C  \'' ri  and  Q  =  Av. 


Depth 
in 
Feet. 

Bed  -width,  3  Feet. 

Bed  -width,  5  Feet. 

Bed-width,  10  Feet. 

A 

r 

\/7 

A 

r 

\/7 

A 

r 

V7 

I 
i-5 

2 

2-5 
3 
3-5 
4 

4-5 
5 

3 

4 
4-5 
5 

I'5 
6-5 
7 

l-s 

9 

10 

3 
4-50 
6 

7-5° 
9 

.600 

-75° 
-857 
-937 
9 

-774 
.866 
.926 
.967 

i 

5 
7-5 

10 

I2-5 
i5 
17-5 

20 

.714 

-937 
i.  in 
1.250 
1.364 
1.458 
1-538 

-845 
.968 
1.054 
1.118 
1.168 
1.208 
1.241 

20 
25 
3° 
35 
40 

45 
50 

1.429 
1.666 

1-875 
2.058 

2.222 
2.367 

2-5 

1-195 
.290 

-396 

-434 
.490 

-538 
.581 

Bed-width,  20  Feet. 

Bed-width,  40  Feet. 

Bed-width,  60  Feet. 

A 

r 

V7 

A 

r 

VT 

A 

r 

V7 

60 

80 
90 

IOC 

no 

120 

2.307 
2.857 
3-I05 
3-333 
3-553 
3-750 

•^8 
.690 

.762 
.825 
-885 
-937 

160 

1  80 

200 
220 
24O 

3-333 
3.672 

4 

4-314 
4.614 

1.826 

1.916 

2 

2.077 
2.148 

240 
270 
300 
330 
360 
390 
420 

45° 
480 
540 
600 

3-529 
3-913 
4.286 
4.646 

5 
5-343 
5-676 
6 
6.316 
6.923 
7-5oo 

1.878 
1.978 
2.073 

2-155 
2.236 

2-311 
2-382 
2.450 

2-SI3 
2.963 

2-738 

280 

5.180 

2.276 

320 
360 

5-7r4 
6.207 

2-394 
2.491 

DISCHARGE   QF    STREAMS   AND   VELOCITIES 


67 


TABLE  XII. 

VALUES   OF  A    IN  SQUARE    FEET,    f   IN   FEET,  AND 
CHANNELS  HAVING  SIDE  SLOPES   OF   I    ON    I. 

For  Use  in  Kutter's  Formula  v  =  C  \/ri  and  Q  =  Av. 


FOR 


Depth 
in 
Feet. 

Bed  -width,  3  Feet. 

Bed  -width,  5  Feet. 

Bed-width,  10  Feet. 

A 

r 

v/7 

A 

r 

V7 

A 

r 

VT 

I 

i-5 

2 
2-5 

3 
3-5 
4 
4-5 

5 

2 

3 
3-5 
4 
4-5 

5 
5-5 
6 

8 

4 

56 
6-5 

7 

I'5 
8-5 
9 
10 
ii 

12 

4 
6-75 

10 

13-75 
18 

.686 
-932 
I-I55 
1-365 
1-567 

.828 
.965 

r-°75 
1.168 
1.252 

6 
9-75 
14     ' 
18-75 
24 
29-75 
36 

.766 
-054 
-314 

-553 
.780 

-997 
2.207 

-875 
.027 

.147 
.246 

-334 
-413 
.486 

24 

31-25 
37-00 

47-25 
56 
65-25 

75 

1-533 
1.831 

2.  IIO 

2-375 
2.628 
2.871 
3-!07 

-238 
-353 
-452 
-541 
.621 

.694 
•763 

Bed-width,  15  Feet. 

Bed-width,  20  Feet. 

Bed-width,  40  Feet. 

A 

r 

VT 

A 

r 

v^7 

A 

r 

x/7 

34 
54 
64-75 
76 

87-75 

IOO 

1.646 
2.300 
2.601 
2.888 
3-l65 
3-431 

.283 
.516 
.612 
.700 

-779 
-852 

69 

96 
110.25 

"5 

140.25 

156 

2.422 

3.066 

3-369 
3.661 

3-944 
4.220 

i-556 

i-75i 
1-835 
1-913 
1.986 
2.054 

176 
200.25 
225 
250.25 
276 
329 
384 

3-431 
3-798 
4-155 
4-504 
4-844 
5-5oi 
6.132 

1.852 
1.949 
2.038 

2.122 
2.201 

2-343 
2-476 

126 

3-941 

1.985 

Bed-width,  60  Feet. 

Bed-width,  80  Feet. 

Bed-width,  100  Feet. 

A 

r 

\n 

A 

r 

vT 

A 

r 

VT 

256 

325 
396 
432-25 
469 
506.25 
544 
582.25 
621 
700 

3-590 
4-384 
5-145 
5-515 
5-877 
6.234 
6.584 
6.928 
7.267 
7.929 

1.895 
2.095 
2.268 
2.348 
2.424 

2-497 
2.566 
2.632 
2.696 
2.816 

425 
5i6 
562.25 
609 
656.25 
7°4 
752-25 
80  1 
900 

IOOI 

4-5J4 
5-321 
5-715 

6.102 

6.484 
6.860 

7.230 

7-595 
8.312 
9.009 

2.125 
2.307 
2.391 
2.470 
2-546 

2.619 

2.689 
2-756 
2.883 

3-oor 

525 
636 
692.25 

749 
806.25 
864 
922-25 
981 

I  IOO 
1221 

1344 

4.600 

5-437 
5.848 
6-252 
6.652 
7.046 
7-435 
7-8i9 
8-575 
9-3J3 
10.03 

2-145 
2-331 
2.418 
2.500 

2-579 
2-654 
2.726 
2.796 
2.928 
3-051 
3-l67 

68        FLOW  AND   MEASUREMENTS   IN   OPEN   CHANNELS 

of  the  mass  owing  to  the  retarding  effect  of  friction  against  the 
atmosphere.  This  velocity  is  known  as  the  surface  velocity. 
The  velocities  of  the  films  adjacent  to  the  sides  and  bottom  of  the 
channel  are  retarded  to  a  still  greater  extent  by  the  roughness  of 
the  same,  and  in  direct  proportion  to  this  roughness.  It  has  been 


TABLE  XIII. 

VALUES  OF  A   IN  SQUARE    FEET,   r  IN   FEET,   AND  \ff  FOR 
CHANNELS   HAVING   SIDE    SLOPES   OF    I    ON    ij. 

For  Use  in  Kutter's  Formula  v  =  C\/ri  and  Q  =  Av . 


Depth 
in 
Feet. 

Bed  -width,  3  Feet. 

Bed-width,  5  Feet. 

Bed-width,  10  Feet. 

A 

r 

V7 

A 

r 

V7 

A 

r 

VT 

I 
1-5 

2 
2-5 

3 
3-5 
4 

4-5 
5 

t 

j 

3 
4 

4-5 
5 

56'5 
6-5 
7 

7-5 
8 

9 

10 

4-5° 
7.87 

12 
16.87 
22.50 

.681 

-935 
i-i75 
1-405 
1.628 

-83 
-97 
i.  08 
1.19 
1.28 

6-5 

10.87 
16 
21.87 
28.5 
35-87 
44 

-755 
1.045 
1.310 
1.560 
1.802 
2.036 
2.266 

.87 
i.  02 
-15 
-25 
-34 
-43 
-51 

26 
34-375 
43-5 
53-375 
64 
73-375 
87-5 

1.510 
1.807 
2.090 
2-358 
2.620 
2.873 

3-I2I 

-23 
-34 
-44 
-54 
.62 
.70 
-77 

Bed-width,  20  Feet. 

Bed-width,  40  Feet. 

Bed-width,  60  Feet. 

A 

r 

x/7 

A 

r 

\/7 

A 

r 

V7 

73-5° 
104 
120.37 
137-5 
155-37 
J74 

2.386 
3.021 
3-332 
3-6i5 
3.901 
4.179 

-54 
-73 
.82 
.90 

-97 

2.04 

184 
210.37 
237-50 
265-37 
294 
323-4 
353-5 

3-399 
3-742 
4.094 

4-435 

4.770 

5-097 
5-4i8 

1.84 

i-93 
2.03 

2.  II 

2.18 
2.26 

2-33 

264 

300.37 
337-5° 
375-37 
414 

453-37 
493-50 
534-37 
576 
661.50 
750 

3-547 
3-94i 
4-325 
4.702 

5-071 
5-434 
5-789 
6.139 
6.483 

7-*55 
7.808 

1.88 
1.99 
2.08 
2.17 
2.25 

2-33 

2.40 

2-47 
2-54 
2.67 

2-79 

416 
481.5 

6.043 
6.646 

2.46' 

2.58 

found  that  in  a  channel  of  trapezoidal  cross-section,  with  an 
average  depth  to  width,  the  film  of  water  having  a  mean  velocity 
of  the  entire  channel  is  located  in  the  centre  of  the  channel  and 
at  a  point  about  one-third  of  the  depth  below  the  surface. 


DISCHARGE   OF    STREAMS   AND   VELOCITIES 


69 


TABLE  XIV. 

VALUES    OF    C     FOR    GIVEN    SLOPES,  I,    AND    HYDRAULIC    MEAN 
RADII,   f,    IN    FEET. 


r 

Coefficients 

of  Roughness 

for  n 

= 

.009 

.OIO 

.012 

.015 

.020 

.025 

.030 

•035 

Feet. 

C 

C 

C 

C 

C 

C 

C 

C 

.1 

no 

95 

74 

54 

36 

27 

21 

17 

.2 

130 

114 

90 

67 

46 

34 

27 

22 

-4 

133 

107 

82 

57 

44 

35 

29 

Slope  f=.oi  = 

.6 

162 

U3 

116 

90 

64 

49 

39 

33 

i  in  100  = 

.8 

i 

170 
175 

156 

123 
128 

95 
99 

68 
72 

43 
45 

II 

2 

191 

171 

142 

112 

83 

66 

55 

46 

52.8  feet  per  mile. 

3 

199 

179 

149 

119 

89 

71 

59 

4 

204 

184 

154 

"3 

93 

76 

55 

6 

210 

190 

160 

129 

99 

81 

68 

59 

10 

217 

196 

166 

136 

105 

86 

74 

65 

.i 

no 

94 

73 

54 

36 

27 

21 

17 

.2 

129 

"3 

89 

66 

45 

34 

27 

22 

Slope  i=  .001  = 

•4 
.6 

161 

142 

"5 

80 
88 

56 

ti 

34 
39 

28 
32 

i  in  1000  = 

.8 
i 

169 

175 

155 

122 
127 

94 
99 

7i 

S2 
56 

42 

45 

II 

2 

191 

171 

142 

112 

83 

66 

54 

46 

5.28  feet  per  mile. 

3 

199 

179 

149 

119 

89 

71 

59 

51 

4 

204 

184 

154 

124 

93 

75 

54 

6 

211 

190 

l6o 

130 

99 

81 

68 

59 

10 

218 

197 

I67 

136 

105 

87 

74 

65 

.i 

104 

89 

69 

5° 

34 

25 

19 

16 

.2 

126 

no 

87 

65 

44 

32 

25 

21 

-4 

148 

129 

104 

79 

55 

42 

33 

27 

Slope  *=.ooo4= 

.6 

157 

140 

"3 

87 

62 

47 

38 

31 

.8 

1  66 

148 

121 

93 

67 

42 

35 

i  in  2500= 

i 

172 

154 

125 

98 

70 

55 

45 

37 

2 

190 

170 

141 

112 

83 

65 

54 

45 

2.  1  1  feet  per  mile. 

3 

199 

179 

149 

119 

89 

71 

59 

4 

204 

184 

124 

94 

76 

63 

55 

6 

211 

191 

161 

130 

99 

81 

69 

60 

10 

219 

199 

168 

138 

107 

88 

75 

66 

.2 

76 

57 

39 

29 

23 

19 

•4 

... 

95 

72 

5° 

38 

25 

.6 

105 

81 

57 

44 

35 

3° 

Slope  z=.oooi  = 

.8 

... 

... 

114 

88 

63 

48 

39 

33 

i 

... 

... 

120 

93 

67 

52 

42 

35 

i  in  10,000= 

2 

... 

138 

109 

81 

64 

53 

45 

3 

... 

... 

149 

119 

89 

71 

59 

51 

.528  feet  per  mile. 

4 

... 

... 

I25 

94 

76 

64 

55 

6 

... 

^64 

IO2 

84 

71 

61 

10 





J74 

J43 

III 

92 

78 

69 

15 

... 

... 

181 

150 

118 

98 

85 

75 

70          FLOW  AND   MEASUREMENT   IN   OPEN   CHANNELS 

81.  Surface  and  Mean  Velocities. — The  surface  velocity  is 
that  which  is  most  easily  obtained  by  simple  methods.     Numer- 
ous experiments  have  been  made  by  Du  Buat,  Francis,  Brunning, 
Humphrey  and  Abbott,  and  others,  to  obtain  the  ratio  of  the  mean 
to  the  surface  velocity.     From  these  it  has  been  found  that  this 
ratio  varies  chiefly  between  ^  =  .7807  and  v  =  .g2oV,  in  which 
v=  the  mean  velocity  of  the  entire  cross-section  of  the  channel  and 
V=  its  central  or  maximum  surface  velocity.     This  ratio  varies 
with  the  section  of  the  channel  and  the  roughness  of  its  sides,  as 
well  as  with  the  depth.     It  is  found  that  the  ratio  of  v  to  V  should 
be  at  a  maximum  when  the  breadth  equals  twice  the  depth,  also, 
for  several  sections,  for  that  which  is  largest.     When  breadth  is 
equal  to  three  times  the  depth,  v=.giV',  when  breadth  is  equal 
to  five  times  the  depth,  ?;  =  .88F;   when  breadth  is  equal  to  eight 
times  the  depth,  ^  =  .837;  in  flood  work,  ^  =  .90  to  .957. 

82.  Measuring  or  Gauging  Stream  Velocities. — One  of  the 
simplest  •  methods  of  gauging  the  velocity  of  a  stream,  but  one 
which  does  not  give  the  most  accurate  results,  is  by  means  of 
simple  wooden  floats  or  bottles,  or  some  similar  contrivance, 
thrown  into  the  centre  of  the  stream  and  timed  for  a  given  dis- 
tance.    For  convenience  100  feet  may  be  measured  off  on  the 
bank  and  the  time  of  the  float  ascertained  in  passing  over  this  dis- 
tance.    For  increased  accuracy  several  passings  of  the  float  over 
this  distance  should  be  measured,  or,  better  still,  the  time  of  pass- 
ing of  floats  over  several  different  lengths  of  100  feet  should  be 
determined.     The  mean  of  these  observations  will  give  the  central 
or  maximum  surface  velocity,  which  multiplied  by  the  proper 
ratio  above  will  give  the  mean  velocity  v.     The  mean  surface 
velocity  may  be  obtained  by  throwing  in  a  number  of  floats  on 
different  portions  of  the  surface  of  the  stream  and  timing  their 
passage  over  a  fixed  distance.     The  resulting  velocity  per  second 
multiplied  by  .8  will  give  approximately  the  mean  velocity  of  the 
entire  stream  cross-section. 

The  velocity  of  a  stream  may  be  ascertained  with  still  greater 
accuracy  by  determining  the  mean  velocity,  not  of  the  surface  as 
above,  but  of  the  entire  body  of  the  stream,  by  timing  upright 
rods  so  weighted  that  their  bottoms  shall  float  within  a  few  inches 


MEASURING   OR   GAUGING    STREAM   VELOCITIES  71 


FIG.  4. — Price  Electric  and  Acoustic  Current  Meters. 


72          FLOW   AND   MEASUREMENT   IN   OPEN   CHANNELS 

of  the  bed  of  the  channel.  These  rods  may  be  either  of  wood  or 
of  tin,  of  uniform  size,  and  may  be  jointed  so  as  to  be  of  con- 
venient use  in  different  depths  of  water.  In  using  the  Pitot  tube 
the  stream  should  be  cross-sectioned  as  in  other  velocity  deter- 
minations, and  the  mean  velocities  may  then  be  ascertained  by 
the  tube  for  various  sections  in  the  channel. 

A  curious  but  well-known  fact  concerning  rivers  in  great  flood 
is  that  the  water  surface  near  the  center  of  the  channel  is  curved 
convexly  upward  and  is  considerably  higher  than  near  the  stream 
banks.  This  fact  should  be  taken  into  account  in  estimating  the 
discharge  of  a  stream  in  flood  if  the  gauge  height  is  measured 
near  the  shore. 

83.  Current  Meters. — Current  meters  are  mechanical  con- 
trivances so  arranged  that  by  lowering  them  into  a  stream  the 


FIG.  5.— Haskell  Current  Meter. 

velocity  of  its  current  can  be  ascertained  with  accuracy  by  a 
direct  reading  of  the  number  of  revolutions  of  a  wheel,  and  a 
comparison  of  this  with  a  table  of  corresponding  velocities. 
Various  forms  of  current  meters  have  been  designed  and  used, 
the  three  general  classes  being  the  direct-recording  meter,  in 
which  the  number  of  revolutions  is  indicated  on  a  series  of  small 
gear-wheels  driven  directly  by  a  cog-and-vane  wheel;  the  electric 
meter,  in  which  the  counting  is  done  by  a  simple  make-and- 
break  circuit,  the  registering  contrivance  being  placed  at  any 
desired  distance  from  the  meter;  and  the  acoustic  meter,  in 
which  counting  is  done  by  hearing  through  an  ear-tube  the  clicks 
made  by  the  revolutions  of  a  wheel  and  counting  the  same. 
Of  electric  meters,  the  Haskell  Meter  (Fig.  5)  is  strongly 


CURRENT    METERS 


73 


made,  simple  and  reliable,  and  therefore  especially  adapted  to 
work  in  large  rivers.  This  meter  is  not  so  good  for  very  high 
velocities  as  that  next  described,  as  the  rapidity  of  revolution  is 
so  great  as  to  make  counting  difficult,  though  it  is  sometimes 
provided  with  two  heads  of  different  pitch  and  rating  for  low  and 
high  velocities. 

The  electric  meter  which  has  been  found  to  work  most  satis- 
factorily under  nearly  all  conditions  of  depth  and  velocity  by  the 
hydrographers  of  the  U.  S.  Geological  Survey  and  U.  S.  Engineer 
Corps  is  the  small  Price  electric-current  meter  (Fig.  4).  It  is 
very  accurate  for  streams  of  nearly  any  velocity,  and  is  practically 
standard  with  both  organizations.  Each  revolution  of  the  wheel 
is  indicated  by  a  sounder,  consisting  of  a  telephone  receiver  excited 
by  a  small  battery  cell.  Two  small  insulated  wires,  attached  to 
the  stem  and  to  the  contact  spring  in 
the  head,  are  connected  with  the 
sounder  through  the  suspending  cable. 

The  Price  acoustic  current  meter  is 
a  modification  of  the  Price  electric  meter. 
It  is  especially  desirable  for  its  portabil- 
ity and  ease  of  handling  as  it  weighs  but 
little  over  a  pound.  In  very  shallow 
streams  it  gives  the  most  accurate  re- 
sults of  ( any  meter,  and  is  held  at  the 
proper  depth  by  a  metal  rod  in  the  hands 
of  the  observer.  It  is  designed  especially 
to  stand  hard  knocks  which  may  be  re- 
ceived in  turbid  irrigation  waters,  and 
can  be  used  in  high  velocities,  as  only 
each  tenth  revolution  is  counted.  Its 
head,  like  that  of  the  electric  meter,  consists  (Fig.  6),  of  a  strong 
wheel  composed  of  six  conical-shaped  cups,  which  revolve  in  a 
horizontal  plane;  its  bearings  run  in  two  cups  holding  air  and 
oil  in  such  manner  as  entirely  to  exclude  water  or  gritty  matter. 
Above  the  upper  bearing  is  a  small  air-chamber,  into  which  the 
shaft  of  the  wheel  extends.  The  water  cannot  rise  into  this  air- 
chamber,  and  in  it  is  a  small  worm-gear  on  the  shaft,  turning  a 


FIG.  6. — Price  Acoustic 
Current  Meter. 


74        FLOW   AND   MEASUREMENT   IN   OPEN   CHANNELS 

wheel  with  twenty  teeth.  This  wheel  carries  a  pin  which  at 
every  tenth  revolution  of  the  shaft  trips  a  small  hammer  against 
the  diaphragm  forming  the  top  of  the  air-chamber,  and  the 
sound  produced  by  the  striking  hammer  is  transmitted  by  the 
hollow  plunger-rod  through  a  connecting  rubber  tube  to  the 
ear  of  the  observer  by  an  ear-piece.  The  plunger-rod  is  in  2- 
foot  lengths,  and  is  graduated  to  feet  and  tenths  of  feet,  thus 
rendering  it  serviceable  as  a  sounding  or  gauging  rod. 

84.  Gauging  Stations. — The  first  operation  in  making  a 
careful  gauging  of  velocity  by  means  of  a  current  meter  is  the 
choosing  of  a  good  station.  This  consists  in  finding  some  point 
on  the  course  of  the  stream  where  its  bed  and  banks  are  nearly 
permanent,  the  current  of  moderate  velocity,  and  the  cross- 
sections  are  uniform  for  over  200  feet  above  and  below  the  gaug- 
ing station.  At  this  point  a  wire  should  be  stretched  across  the 
stream  and  tagged  with  marks  placed  every  5,  10,  or  20  feet 
apart,  according  to  the  width  of  the  stream.  An  inclined  gauge- 
rod  is  firmly  set  into  the  stream  at  some  point  where  it  can  be 
easily  reached  for  reading.  It  should  not  be  less  than  4  by  4 
inches  and  marked  for  feet  and  tenths  of  vertical  depth.  The 
gauge  heights  are  recorded  through  a  long  period  of  time  in  order 
that  variations  in  the  velocity  and  discharge  may  be  had  for 
different  flood  heights. 

Fluctuations  in  the  heights  of  streams  may  be  measured 
with  even  more  accuracy  than  can  be  obtained  by  the  readings 
of  a  gauge-rod  as  above  described  by  using  a  nilometer,  which 
is  a  self-recording  gauge.  The  chief  objection  to  the  use  of  this 
instrument  is  that  its  maintenance  requires  the  attention  of  a 
person  of  considerable  mechanical  skill  in  order  that  it  may  be 
kept  in  proper  order.  There  are  three  general  forms  of  nilo- 
meter employed  by  the  hydrographers  of  the  United  States  Geo- 
logical Survey.  These  have  horizontal  recording  cylinders, 
vertical  recording  cylinders,  and  vertical  record  disks.  All 
of  these  devices  are  driven  by  clockwork  and  are  designed  to 
run  a  week  before  renewal  of  recording  paper.  The  record 
of  stream  height  by  the  nilometer  is  on  a  scale  less  than  the  actual 
range  of  the  water,  and  the  recording  pencil  is  connected  by 


USE     OF     THE    CURRENT    METER 


75 


a  suitable  reducing  device  with  a  float  which  rises  or  falls  with 
the  stream.  This  float  is  usually  placed  in  a  small  well  near  the 
stream-bank,  its  bottom  communicating  with  the  stream-bed 
by  a  pipe  of  such  size  as  will  not  become  readily  clogged.  The 
fluctuations  of  the  water  in  this  pipe  correspond  with  those  in 
the  stream  and  turn  the  recording  wheel  through  the  agency  of 
a  cord  wound  around  the  wheel  and  having  its  lower  end  attached 
to  the  float. 

85.  Use  of  the  Current  Meter. — The  current  meter  may  be 
conveniently  used  either  from  a  boat  attached  to  a  wire  cable 


FIG.  7. — Cable  Station  and  Section  of  River. 

strung  a  little  above  the  tagged  wire,  or  from  a  bridge  which 
does  not  impede  the  channel  so  as  to  make  currents  or  eddies 
in  the  water. 

In  using  the  acoustic  meter  the  gauger  holds  it  in  his  hands 
by  the  rod,  and  inserting  it  in  the  water  at  any  desired 
depth  allows  it  to  register  for  a  certain  number  of  seconds.  In 
obtaining  the  mean  velocity  of  the  stream  he  plunges  it  slowly 
up  and  down  from  the  bottom  of  the  stream  to  its  surface  a  few 
times  for  a  given  length  of  time  at  each  section  marked  on  the 
tagged  wire,  and  in  this  way  gets  the  mean  velocity  of  each  section. 
The  area  of  this  section  is  of  course  already  ascertained,  by  a 
cross-section  made  by  measurement  or  sounding  of  the  stream, 
and  the  mean  velocity  multiplied  into  the  area  of  each  section 
gives  the  discharge  at  that  point.  Care  must  be  taken  to  hold 


76         FLOW   AND   MEASUREMENT   IN    OPEN   CHANNELS 

the  rod  vertically,  as  any  inclination  of  the  meter  materially 
affects  its  record. 

In  using  the  electric  meter  it  is  inserted  in  the  same  manner 
for  moderately  shallow  streams,  but  in  deep  flood  streams  it  is 
suspended  by  a  wire  and  a  very  heavy  weight  is  attached  to  its 
bottom  to  cause  it  to  sink  vertically. 

86.  Rating  the  Meter. — Before  the  results  can  be  obtained 
each  meter  must  be  rated ;  that  is,  the  relation  between  the  num- 
ber of  revolutions  of  the  wheel  and  the  velocity  of  water  must 
be  ascertained.     This   is  usually  done  by  drawing  the  meter 
through  quiet  water  over  a  course  the  length  of  which  is  known, 
and  noting  the  time.     From  the  observations  thus  made  the 
rating  is  determined  either  by  formula  or  by  graphic  solution. 
The  distance  through  which  the  meter  is  drawn  divided  by  the 
time  gives  the  rate  of  motion  or  velocity  of  the  meter  through 
the  water.     The  number  of  revolutions  of  the  wheel  divided 
by  the  time  gives  the  rate  of  motion  of  the  wheel.     The  ratio  of 
these  two  is  the  coefficient  by  which  the  registrations  are  trans- 
formed into  velocity  of  the  current.     This  is  not  a  constant. 
Taking  the  number  of  registrations  per  second  as  abscissae  repre- 
sented by  x,  and  the  velocity  in  feet  per  second  as  ordinates 
represented  by  y,  we  get  the  equation  y  =  ax  +  fr,  in  which  a  and  b 
are  constants  for  the  given  instrument. 

In  determining  the  rating  of  the  meter  graphically,  the  values 
of  x  and  y  gotten  directly  from  the  instrument  are  plotted  as 
co-ordinates,  using  the  revolutions  per  second  as  abscissae  and 
the  speed  per  second  as  ordinates.  In  this  way  a  series  of  points 
are  obtained  through  which  a  connecting  line  called  a  rating- 
curve  is  drawn.  From  this  the  coefficient  of  velocity  can  be  read 
off  corresponding  to  one,  two,  or  any  number  of  revolutions  per 
second.  At  each  rate  of  speed  of  the  meter  there  is  a  different 
coefficient  of  velocity.  Three  or  four  of  these  for  average  varia- 
tions in  velocities  may  be  used  in  getting  the  true  velocity  from 
the  meter  record. 

87.  Rating  the  Station. — After  daily  readings  of  the  gauge 
height  of  the  water  have  been  taken  at  the  station  for  some  time, 
and  the  velocity  measured  by  means  of  the  meter  at  different 


MEASURING   WEIRS  77 

heights  of  stream,  the  results  should  be  plotted  on  cross-section 
paper,  with  the  gauge  heights  as  ordinates  and  the  discharges 
(obtained  by  multiplying  the  velocities  into  the  cross-section) 
as  abscissas.  These  points  generally  lie  in  such  a  direction  that 
a  line  drawn  through  them  gives  nearly  half  a  parabolic  curve 
and  represents  the  discharge  for  different  heights.  Having 
once  plotted  this  line  it  becomes  possible  to  determine  the  dis- 
charge of  the  stream  at  any  time  by  knowing  the  height  of  the 
water  from  the  gauge-rod. 

88.  Measuring  Weirs. — The  method  of  measuring  discharge 
which  is  most  popular  among  the  irrigators  because  of  its  simpli- 
city and  accuracy  is  by  means  of  weirs.     This  method  is  best 
suited  to  streams  and  canals  of  moderate  size.     Among  the  ad- 
vantages of  the  weir  as  a  measuring  device  are  its  simple  con- 
struction, accuracy,  cheapness,  and  ease  of  operation.     Its  results 
are  easily  interpreted  by  use  of  tables;  it  gives  quantities  of  flow 
in  second-feet  directly;  it  is  not  necessary  to  maintain  a  constant 
head  above  it;  and  it  causes  a  trifling  loss  of  head. 

Where  the  contraction  is  complete  its  coefficient  remains 
constant,  and  the  Francis  formula  gives  the  discharge  with  errors 
not  exceeding  one-half  of  one  per  cent  for  depths  of  water  vary- 
ing between  3  and  24  inches,  providing  the  length  of  the  weir 
is  not  less  than  three  or  four  times  the  depth  of  the  water  flowing 
over  it. 

There  are  two  classes  of  weirs,  i,  sharp-crested  or  measuring 
weirs  and  2,  broad-crested  weirs  or  overflow  dams.  The  three 
forms  of  measuring  weirs  which  are  most  popular  are  i,  the 
rectangular  weir  with  vertical  sides,  2,  the  trapezoidal  and  3,  V 
weirs,  of  which  the  latter  two  have  inclined  sides  with  slopes  of 
about  one-fourth  horizontal  to  one  vertical. 

89.  Rectangular    Measuring    Weir. — The     measuring     weir 
(Fig.  8)  should  be  placed  at  right  angles  to  the  stream,  with  its 
up-stream  face  in  a  vertical  plane.     The  crest  and  sides  should 
be  chamfered  so  as  to  slope  downward  on  the  lower  side  with  an 
angle  of  not  less  than  30°,  while  the  crest  should  be  practically 
horizontal  and  the  ends  vertical.     The  dimensions  of  the  notch 
should  be  sufficient  to  carry  the  entire  stream  and  yet  leave  the 


78 


FLOW   AND   MEASUREMENT   IN   OPEN   CHANNELS 


depth  of  water  on  the  crest  not  less  than  five  inches.  The  sec- 
tional area  of  the  jet  should  not  exceed  one-fifth  that  of  the 
approaching  stream.  In  order  that  the  proper  proportion  of 
the  area  of  the  notch  to  that  of  the  jet  shall  be  maintained,  central 


FIG.  8.  —  Rectangular  Measuring  Weir. 

contractions  may  be  introduced,  dividing  the  weir  crest  into 
several  orifices. 

90.  Francis*    Formulas.  —  The   form    of    equation    indicated 
by  theory  for  the  discharge  of  a  weir  is 

Q  =  Av;  ........      (ii) 

or,  substituting  for  the  mean  velocity  v  of  a  given  film  its  value 
§\/2g/£,  and  for  A  the  area,  its  equivalent  /  X  h,  we  get 

Q  =  lXhX$V^>h,     ......     (13) 

which  formula  may  be  transposed  so  as  to  become 


where  /  is  the  effective  length  of  the  weir  in  feet,  and  h  the  depth 
in  feet  of  water  flowing  over  it.  Because  of  the  downward  curve 
of  the  water  after  passing  over  the  weir,  this  height  h  must  be 
measured  at  some  distance  above  the  weir,  in  order  to  be  free 
from  its  influence.  The  reduction  of  volume  by  the  crest  con- 
traction can  be  compensated  for  by  the  coefficient  m,  and  insert- 
ing this  factor  in  formula  (14)  we  have 

Q  =  $mV^>lh*.   „•/  .   ,4,,  :•  •-.;  -     -     (15) 

The  factors  \m  and  V~2g  are  constants,  and  representing  them 
by  c  we  can  substitute  it  in  the  formula  as  a  coefficient.  This 
is  the  coefficient  which  was  determined  to  be  equal  to  3.33  by 
Mr.  J.  B.  Francis'  experiments,  and  substituting  this  value  in 
equation  (15)  we  get 


CONDITIONS    OF   USING   RETANGULAR   WEIRS  79 

Owing  to  this  falling  away  of  the  surface  at  the  crest  and  to  the 
contraction  at  the  ends,  if  /'  be  the  effective  length  of  the  weir, 
one  end  contraction  makes  /'  =  (/  —  o.i/z),  and  any  number  of 
end  contractions  make  /'  =  (/  —  o.inh).  Hence 


....     (17) 

which  is  Francis'  formula. 

91.  Conditions    of    using    Rectangular    Weir.  —  If    the    weir 
be  placed  so  as  to  meet  the  following  conditions,  formulas  (16) 
and  (17)  will  give  the  best  results.     These  conditions  are:   that 
the  water  shall  not  exceed  24  or  be  less  than  4  inches  in  depth; 
that  the  depth  on  the  crest  shall  not  exceed  one-third  the  length 
of  the  weir;    that  there  shall  be  complete  contraction  and  free 
discharge;  and  that  the  water  shall  approach  without  perceptible 
velocity  or  cross-currents.     To  obtain  these  conditions  the  dis- 
tance from  the  side  walls  to  the  weir  opening  should  be  at  least 
equal  to  twice  the  depth  on  the  weir;   and  the  distance  of  the 
crest  above  the  bottom  of  the  channel  should  be  at  least  twice 
the  depth  of  water  flowing  over  it.     Air  should  have  free  access 
under  the  falling  water,  and  the  approaching  channel  should 
be  at  least  seven  times  larger  than  the  weir  opening.     The  ap- 
proaching channel  should   be  straight  and   of   uniform  cross- 
section.     The  weir  should  be  erected  in  a  plane  at  right  angles 
to  the  stream  and  perpendicular  to  its  bed,  and  the  edges  of  the 
opening  should  be  sharp  up-stream  and  cut  away  down-stream. 

92.  Trapezoidal  Weirs.  —  As  a   result  of  experiments   made 
in  Italy  in  1886  by  Cippoletti,  he  adopted  a  trapezoidal  weir 
the  sides  of  which  have  an  inclination  of  one-fourth  horizontal 
to  one  vertical.     This  is  based  on  the  theory  that  the  effective 
length  /  of  a  rectangular  weir  being  less  than  its  true  length  ow- 
ing to  contraction,  if  the  area  of  the  weir  be  increased  in  propor- 
tion to  its  depth  (since  contraction  increases  in  this  ratio)  and 
so  as  to  balance  the  loss  due  to  contraction,  the  flow  through 
the  weir  will  remain  the  same  as  though  the  weir  were  rectangular 
without   contraction.     The  conditions  called  for  in   placing  a 
rectangular  weir  must  be  nearly  fulfilled  with  a  trapezoidal  weir, 
but  the  distance  of  the  sill  of  the  weir  from  the  bottom  of  the 


80         FLOW   AND    MEASUREMENT    IN    OPEN    CHANNELS 

canal  must  be  at  least  three  times  the  depth  of  the  weir,  and 
its  length  must  be  at  least  three  times  the  depth  of  the  water 
flowing  over  it.  In  using  this  form  of  weir  the  equation  becomes 

<2=  3-3W& (18) 

This  weir  seems  to  possess  some  excellent  qualities,  the  chief 
difficulty  in  connection  with  it  being  the  same  as  arises  in  using 
the  rectangular  weir,  namely,  that  where  silt-laden  water  is 
employed  this  may  fill  up  above  the  front  board  of  the  weir. 
This  weir  (Fig.  73)  may  be  used  as  a  divisor,  and  for  fairness 
of  measurement  is  especially  adapted  to  use  on  irrigation  canals. 
In  using  a  triangular  weir  a  convenient  formula  has  been 
found  to  be  the  following : 

Q=  2.$4th*, (19) 

in  which  t  is  the  tangent  of  half  the  angle  in  the  notch  of  the 
triangle.  If  the  triangle  be  right-angled,  this  formula  becomes 

<2=2.54/*%      . (20) 

which  is  one  of  the  simplest  formulas  that  can  be  used,  and  gives 
excellent  results  on  small  streams. 

93.  Weir  Gauge  Heights. — In  order  to  determine  the  depth 
of  water  flowing  over  the  weir  a  post  should  be  set  in  the  stream 
a  short  distance  above  it,  and  on  this  a  gauge  rod  suitably  marked 
should   be    attached.     For    very   exact   measurements  a    hook 
gauge  has  been  employed,  which  consists  of  a  hook  attached  to  a 
sliding  rule  fastened  or  hung  so  that  its  point  shall  be  below  the 
surface  of  the  water.     By  turning  a  tangent  screw  the  hook  can 
be  raised  until  it  is  exactly  level  with  the  surface,  thus  giving  an 
accurate  measurement  of  the  depth  of  water. 

94.  Tables  of  Weir  Discharge.— Tables  XV  and  XVI  are 
taken  from  Prof.  L.  G.  Carpenter's  instructive  bulletin  on  water 
measurement.     These  tables  give  directly  the  discharge  of  rect- 
angular and  trapezoidal  weirs  of  given  lengths  and  for  given 
depths. 

95.  Broad-Crested   Weirs. — The   results   of   various    experi- 
ments to  determine  coefficients  of  discharge  over  broad-crested 
weirs  have  been  assembled  by  Mr.  R.  E.  Horton.     These  show 


BROAD-CRESTED     WEIRS 


8l 


TABLE  XV. 

DISCHARGE  OVER  RECTANGULAR  WEIRS  OF  VARIOUS  LENGTHS 
AND  WITH  VARIOUS  DEPTHS  OF  WATER,  WITH  AND  WITHOUT 
CONTRACTION. 

Formula,  Q  =  3.33$  (/ — o.2/z)/*2. 


DISCHARGE  IN  CUBIC  FEET  PER  SECOND. 

Depth  of 
Water  on 

Correction    to 

Crest. 

With  Two  Complete  Contractions. 

be  ADDED  to 

each   of   the 

preceding 

to   give   dis- 

In 

In 

charge    with 

inches. 

feet. 

/=!    ft. 

/=i-5  f 

1=2   ft. 

/  =  3  ft. 

/  =  sft. 

/=ioft. 

NO    contrac- 

tion. 

0.3 

.025 

•  0133 

.0200 

.O276 

.0400 

.0677 

•133 

.0000 

0.6 

.050 

.0369 

•0556 

•0743 

.1116 

.1863 

•3726 

.0004 

0.9 

•  075 

.0674 

.1015 

.1350 

.  2040 

.3410 

.6830 

.0010 

I  .2 

.  i 

.1033 

•1550 

.2078 

•  3132 

•  5240 

I.05I9 

.0021 

i  -5 

•125 

.1438 

•  2175 

.2912 

•4385 

.7332 

I-4695 

.0037 

1.8 

•IS 

.1879 

•  2847 

.38l6 

•  5743 

.9627 

1  .  93  1  2 

.0058 

2  .  I 

•175 

•  2355 

•  3575 

•  4795 

•  7235 

I.  2115 

2-43I5 

-0085 

2-4 

.  2 

.2861 

•  4352 

•  5843 

.8824 

1.4787 

2.9690 

.0119 

2.7 

.225 

•  3399 

.5177 

.6956 

1.0513 

1.7627 

3-5412 

.0160 

3-o 

•25 

•3959 

.6042 

.8126 

1.2293 

2  .O227 

4-  1462 

.0208 

3-8 

•275 

•4543 

.6946 

•9350 

I.4I57 

2-3771 

4  -  7803 

.0264 

3-6 

•  3 

•  5149 

.7287 

.0725 

i  .6103 

2-7057 

5-4441 

.0328 

3-9 

•325 

•5775 

.8863 

•  1952 

i  .8129 

3.0483 

6.  1368 

.0401 

4-2 

•  35 

.6420 

.9871 

•3423 

2  .O226 

3.4032 

6.8547 

-0483 

4-5 

•  375 

•  7079 

1.0905 

•4732 

2.2385 

3-769I 

7-5956 

•0574 

4.8 

•  4 



.1974 

.6160 

2.4623 

4.1489 

8.3655 

.0674 

5-i 

•425 

.3070 

.7689 

2  .  6926 

4-5400 

9-1585 

•0785 

5  -4 

•45 

.4189 

.9221 

2  .9874 

4  .  9410 

9  .  9725 

OQOC 

5-7 

•475 

•  5333 

.0790 

3.1703 

5-3529 

10.8994 

.  wyw^ 

.1036 

6.0 

.5 

.6500 

•2392 

3.4177 

5-7743 

II  .6672 

.1178 

6.3 

•525 

.7689 

.4029 

3-6709 

6.2069 

12.5469 

•  1331 

6.6 

•55 



.8899 

.5698 

3-9295 

6.6489 

13  .4474 

.1496 

6.9 

•  575 

.0129 

•7395 

4.1928 

7-0995 

14-3658 

.1671 

7-2 

.6 

.1381 

2  .9128 

4.4621 

7-5607 

15-3072 

.1859 

7-5 

.625 



.  2646 

3.0881 

4.7351 

8.0291 

16.2641 

•  2059 

7-8 

•65 

•  3929 

3.2663 

5-0130 

8.5064 

17.2399 

.2271 

8.1 

•  675 



•5234 

3.3478 

5-2965 

8-9939 

18.2374 

.2496 

8.4 

.7 

3  •  63  13 

5  •  5536 

9.4882 

19  .  2497 

•  2733 

8.7 

•  725 

3  .8170 

5  •  7747 

9  .  9901 

20.2786 

2084. 

9  •  ° 

•  75 

4  .  0052 

6  .  i  702 

10  .  5002 

21  .3252 

.  -  u<^4 
.3248 

9  -3 

•  775 

4  .  I  06  I 

6  .  4704 

i  i  .  0190 

22  .  39O5 

7  r  2C 

9.6 

.8 

4  .3884 

6  .  7734 

I  I      CA14 

23  .4684 

•  J  J  *5 
.3816 

9  .9 

.825 

A   c8^^ 

7  .  08  i  o 

x  x  •  j4,54 
I  2  .  0764 

24  «  5649 

.4121 

IO  .  2 

85 

**  •  j°jj 

A.     ?8o6 

TO      AT  i  C 

2C    6?nr> 

10  .  5 

^875 

4  .  youu 
4O7O2 

7  .3929 

77O7  C 

*  *  •  U  *  3  5 
13  .  l64 

^5  *  u/yu 
26  .  8056 

•  444O 

All  A 

10.8 

n 

•  yyy* 

•  /**/  J 

8   02  <7 

T  -2      T  T  TT 

•  4  /  /^ 

5  I  2"l 

1  1  .  i 

•  y 
•  925 

8    ^4.7^ 

13  •  7  1/7 

T  A      277O 

27  *  9477 

2O      T  C\A  A 

!s886 

11.4 

i  ,  - 

°  •  34  /  j 

8  672? 

A4  •  *  /  /  V 

T  1    RA  c  T 

^y  .  L  044 

e86j. 

it.  7 

•  V5 

•  975 

O  .  Uy  ^5 
9.0012 

14  •  "45  * 

15.4192 

3I-4642 

•  5OW4- 
.6258 

82         FLOW  AND   MEASUREMENT  IN  OPEN   CHANNELS 


TABLE  XV. — Continued. 


Depth  of  Water 
on  Crest. 

DISCHARGE  IN  CUBIC  FEET  PER  SECOND. 

With  Two  Complete  Contractions. 

Correction  to  be    ADDED    to 
each    of    the    preceding    to 
give  discharge  with  NO  con- 
traction. 

In  Inches. 

In  feet. 

/  =  3  feet. 

/=5feet. 

l=io  feet. 

12.0 

12.3 

12.6 

12.9 

13-2 
13-5 
13-8 
14.1 

14.4 
14-7 
iS-o 
15-3 

15-6 
iS-9 
16.2 

16.5 

16.8 
17.1 
17-4 
17-7 

18. 
18.3 
18.6 
18.9 

19.2 
19-5 
19  8 

20.  I 

20.4 

20.7 

21 
21-3 

21.6 
21.9 
22  .  2 
22.S 

22.8 
23-1 

23  -4 

23-7 

24 
27 

3° 
36 

o 
025 
05 
075 

i 
125 
150 
i75 

2 
225 
25 
275 

3 

325 
•35 
•375 

•4 
•425 
•45 
•475 

•  5 
•525 
•  55 
•  575 

.6 
.625 
•65 
•  675 

•  7 
•  725 
•  75 
•  775 

.8 
.825 
.85 
.875 

•  9 
•925 
•95 
•975 

•25 
•50 
3 

9-3333 
9.6679 
10.0058 
10.3471 

10.6890 
11.0370 
11.3866 
11.7396 

12.0935 
12.4507 

12  .8l03 
13-1733 

13-5375 
I3-9047 
14.2744 
14.6450 

i  6  .0000 
16.5859 
17.1784 
17.7777 

18.3825 
18.9916 
19.5080 

20.  2308 

20.8569 
21  .4893 
22  .  1269 
22.7713 

23.4189 
24.0727 
24  73l8 
25-3936 

26.0625 
26.6355 
27  .4122 
28.0950 

28.7814 
29.4719 
30.  1675 
30.8681 

3L5727 
32  .  2809 
32  -9935 
33-7093 

34.4269 

35  •  1546 
35-8827 
36.6151 

37  -3520 
38.0709 
38.8341 
39-58i2 

40.3321 
41  .0860 
41-8436 
42-6045 

43-3665 

32.6667 
33-8809 
35-1099 
36.3532 

37.6iio 
38.9781 
40.1615 
4i  -4573 

42.7654 
44-0856 
45.4184 
46.7663 

48.1224 
49.4927 
50.8753 
52.2651 

53  .6710 
55  .0870 
56.5122 
57.9515 

59-3999 
60.8584 
62.3290 
63  .8116 

65.3042 
66.8059 
68.3185 
69-8393 

71  .3710 
72.9146 
74.4662 
76.0286 

77  .6020 
79.1614 
80.7716 
82.3717 

83  .9816 
85  -5995 
87  .2271 
88.8635 

90.5061 
107  .44 
125  .  16 
162.79 

.6667 
.7091 
•  7531 
.7988 

.8460 
.8949 
•  9455 
•  9977 

0516 
1072 
1646 
2237 

2846 
-3473 
-4117 
•  4779 

-5400 
.6160 
.6878 
•  7615 

-8371 
.9146 
.9940 
-0754 

-1588 
-2441 
-3315 
-4207 

.5128 
-6054 
.7008 
-7984 

2.8980 
3  .0196 
3-1034 
3  •  2093 

3-3I74 
3-4275 
3-5399 
3-6545 

3-771 
S.o6 
6-59 
10.39 





BROAD-CRESTED     WEIRS 


TABLE  XVI. 

DISCHARGE  OVER  CIPPOLETTl'S  TRAPEZOIDAL  WEIR  OF  VARIOUS 
LENGTHS   AND   WITH    VARIOUS    DEPTHS. 

Formula,  Q  =  3.365  //tl. 


Depth  of 
Water 
on  Crest. 

DISCHARGE  IN  CUBIC  FEET  PER  SECOND  OVER  WEIR. 

In 
Ins. 

In 
feet. 

/=ift. 

=  i.5ft. 

/-aft 

/=3ft. 

/  =  4ft. 

/=5ft. 

/=7ft. 

/=ioft. 

•  3 
.6 
.    -9 

I  .2 

!:I 

2  .  I 

2-4 
2.7 

3-0 
3-3 

3-6 
3-9 

4.2 
4-5 

4-8 
5-1 
5-4 
5-7 

6.0 
63 
6.6 
6.9 

7-2 

7-5 

I* 

8.4 
8.7 

9-0 
9-3 

9.6 
9-9 

IO.2 

10.5 

10.8 
ii  .  i 
ii  .4 
ii.  7 

12.0 

12.3 

12.6 

12.9 

.025 
•  05 
•075 

.  i 
•125 
•  15 
•175 

.2 
.225 
•25 

•  275 

•3 
•325 

•35 
•375 

•  4 
•  425 
•45 
•475 

-5 
•525 

•55 
5-75 

.6 
.625 
•65 
•675 

.7 
•  725 

•75 
•  775 

.8 
.825 
•85 
•875 

•9 
•  925 
•95 
•  975 

i  .0 
i  .025 
1-05 
1-075 

•  0135 
•  0367 
.0690 

.1064 
.1488 
.1956 
.2464 

.3010 
•3592 
.4208 
•  4855 

•  5531 
.6238 
.6972 
•  7730 

.0202 
.0566 

•1035 

•  1596 
.2232 
•2934 
.3697 

.4515 
.5388 
.6312 
.7282 

.8297 
.9358 
•  0459 
•1595 

•2777 
•3993 
•5246 
•6534 

.7854 
.9210 
•0599 
.2018 

•3472 
•4955 
.6462 
.8007 

.0269 
•  0754 
.1380 

.2128 
.2976 
•  3912 
.4929 

.6020 
.7184 
.8417 
•  9709 

.1063 
•  2477 
•3945 
.5460 

•7035 
.8658 
.0328 
•2045 

.3805 
•  5614 
•  7465 
•9357 

3-1293 
3  -3274 
3-5283 
3-7343 

3-9437 
4-1565 
4-3733 
4-5942 

4.8i77 
5-0453 

.0404 
•  1131 
.2071 

•  3192 
.4464 
.5868 
•7393 

.9029 

i  .0777 
i  .2625 
1.4564 

1.6594 
1-8715 
2.0917 
2.3190 

2-5553 
2-7987 
3-0492 
3-3067 

3-57o8 
3-8420 
4.1198 
4-4036 

4-6939 
4.911 
5-2924 
5-6014 

5-9I56 
6.2347 
6.5599 
6.8912 

7.2265 
7-5679 
7.9154 
8.2669 

8.6234 
8.9850 
9.3516 
9-7233 

10.  IOOO 

10.4808 
10.8666 
11-2575 

•0539 
.  1508 
.2761 

•  4256 
•5952 
-7824 
.9858 

•2039 
•4369 
-6833 
.9419 

.2126 
•4954 
-7890 
3  .0902 

3-407I 
3.73i6 
4-0656 
4-4089 

4.7610 
5-1227 
5-4930 
5-8715 

6.2585 
6.6548 
7-0565 
7.4686 

7-8874 
8.2930 
8  .  7466 
9-1883 

9.6354 
10.0906 
10.5538 
ii  .0225 

ii  .4978 
i  i  .  9800 
12.4688 

I  2  .  9644 

T3-566? 
13  .9744 
14.4888 
15  .OIOO 

•0673 
.1885 
•3451 

•5319 
•  7440 
.978o 
I  .2322 

1.5049 
1.7961 

2  .  I  04  I 
2.4273 

2.7657 
3.II92 
3.4862 

3  •  8649 

4-2588 
4-6645 
5  .0820 
5-5II2 

5-9512 
6.4034 
6.8663 
7-3393 

7.8231 
8.3185 
8.8206 
9-3357 

9-8593 
10.3912 
10.9332 
11.4854 

12.0442 

12  .6132 

13.1923 
13.7781 

14.3723 
14.9749 
15.5860 

16.  2054 

16.8333 
17.4679 
18.1110 
18.7624 

::::::: 

-1347 
•3771 
.6902 

I  .0639 
1.4881 
1  .9560 
2.4644 

3  .  0098 
3-5922 
4  -  2083 
4-8547 

5-53M 
6.2384 
6.9724 
7.7299 

8.5177 
9.3290 
10.  1640 
ii  .0225 

ii  .9025 

I  2  .  8068 
13.7326 
14-6787 

15.6463 

16  .6370 
17  .6413 
18.6715 

19.7186 
20.7824 
21.8665 

22  .9708 

24.0885 
25.2264 
26.3846 
27.5562 

28.7446 
29.9499 
31  .1720 
32.4019 

33-6667 

34   9350 
36.2220 
37.5249 





13  .8030 
14.5477 
15.3065 
16.0796 

16.8619 
17.6585 
18.4692 
19.2893 

2O.  121  2 
20.9649 
21  .82O4 
22.6876 

23.5667 

24.4551 
25-3554 
26.  2674 



84        FLOW    AND    MEASUREMENT  IN   OPEN   CHANNELS 


TABLE  XVI.— Continued. 


Depth  of  Water 
on  Crest. 

DISCHARGE  IN  CUBIC  FEET  PER  SECOND  OVER  WEIR. 

In  ins. 

In  feet. 

/  =  3  feet. 

/  =  4  feet. 

/  =  5  feet. 

1  =  7  feet. 

/=io  feet. 

13-2 
13   5 
13-8 
14.1 

14.4 
14.7 
15-0 
iS-3 

15-6 
iS-9 
16.2 
16.4 

16.8 
17.1 
17.4 
17.7 

18.0 
18.3 
18.6 
18.9 

19.2 
19-5 
19.8 
20.  i 

20.4 
20.7 

21  .O 
21.3 

21.6 
21.9 
22.2 
22.S 

22.8 
23.1 
23-4 
23-7 

24.0 
25-5 
27.0 
28.8 

30.0 

.  i 
•  125 
•  150 
•175 

.  2 
•  225 

-25 

•275 

•  3 
•325 
•35 
•375 

•4 
•425 
•45 
•  475 

•  5 
•525 
•55 
•575 

.6 
•  625 
•65 
.675 

•7 
•  725 
•75 
•  775 

.8 
.825 
•  85 
•  875 

•9 
•925 
•95 
•975 

.0 

•  125 
•25 
•4 

2-775 

11.6524 
12.0513 
12.4553 
12.8644 

13.2764 
13-6936 
14.1148 
14.5410 

15-5365 
16.0684 
16.6071 
17-1525 

17.7019 
18.2581 
18.8197 
19.3880 

19.9603 
20.5394 

21  .  1238 
21.7123 

22.3075 
22.9082 
23.5128 
24.1242 

24.7396 
25.3604 
25.9866 
26.6l82 

19  .4206 
20.0855 
20.7588 

2  I  .  4406 

22.1274 
22.8226 
23.5246 
24.2349 

24.9503 
25.6742 
26.4047 
26  .  1404 

27.8844 
28.6352 
29.3910 
30.1552 

30.9245 
3I-7005 
32.4833 
33-2727 

34.0685 
34.8702 
35.6782 
36.4913 

37-3111 
38.1376 
38.9691 
39.8074 

40.6515 
4I-5009 
42-3577 
43-2179 

27.1888 
28.1198 
29  .0624 
30.0168 

30.9784 
31-9517 
32-9344 
33-9289 

34-9305 
35-9439 
36.9666 
37.9966 

39-0382 
40.0893 
41-1474 
42.2173 

43  •  2943 
44-3808 
45.4766 
46.5818 

47-6959 
48.8183 
49-9495 
51.0878 

52.2355 
53-5926 
54.5568 
55.7304 

56.9121 
58.1013 
59-3008 
60.5031 

61  .7211 
62.9442 
64.  1720 
65  .4116 

66.6560 
72.999 
79-541 
87.619 

03-156 

38.8412 
40.1711 
41  .5177 
42.8812 

44-2548 
45-6453 
47-0492 
48.9699 

49.9007 
51-3484 
52.8095 
54-2808 

55-7688 
57.2704 
58.7820 
60.3105 

6  i  .8490 
63  .4011 
64.9666 
66.5455 

68.1370 
69.7405 
71-3565 
72  .9826 

74.6222 
76.2752 
77.9383 
79.6149 

83-3030 
83.0018 
84.7154 
86.4358 

88.1730 
89.9203 
91  .6743 
93  -4452 

95  .2228 
104.  285 
H3  -63 
125.17 

I33-C8 





MEASUREMENT  OF  CANAL  WATER         85 

that  over  several  types  of  such  weirs,  and  for  any  width  of  cross- 
section  exceeding  2  feet,  the  following  formula  applies: 


This  formula  applies  to  heads  exceeding  six  inches  and  up 
to  twice  the  breadth  of  weir  crest. 

Mr.  E.  C.  Murphy  has  determined  multipliers  to  be  used  in 
finding  the  discharge  over  various  forms  of  broad-crested  weirs 
in  connection  with  Bazin's  formula.  These  and  the  tables  of 
discharges  computed  or  experimentally  determined  have  been 
brought  together  by  Mr.  Horton  in  Bulletin  200  of  the  U.  S. 
Geological  Survey.  (See  also  p.  406.  ) 

96.  Measurement  of  Canal  Water.  —  That  water  flowing  in 
open  canals  may  be  sold  by  quantity  it  is  necessary  that  the 
volume  admitted  to  the  canal  may  be  readily  ascertained  at 
any  time,  and  that  the  method  of  admission  may  be  so  regu- 
lated that  it  cannot  be  tampered  with.     As  no  method  has  yet 
been  devised  for  easily  and  cheaply  accomplishing  this,  water 
is  almost  universally  disposed  of  by  some  means  other  than  by 
quantity.     It  is  customary  in  India  to  charge  a  land  rental  which 
is  dependent  on  the  amount  of  water  used.     In  our  country,  water 
is  regulated  in  accordance  with  the  character  of  the  crop  as  on  this 
rentals  are  charged  per  acre  irrigated  rather  than  by  the  amount 
of  water  required.     In  other  words,  water  is  not  sold  like  other 
commodities  having  intrinsic  value,  by   the   yard,    pound,   or 
gallon.     Numerous  efforts  have  been  made  to  devise  some  cheap 
and  convenient  method  of  measuring  water  at  a  cost  commen- 
surate with  its  value,  but  none  can  as  yet  be  said  to  have  achieved 
success. 

97.  Requisites  of  a  Measuring  Apparatus  or  Module.  —  Prof. 
L.   G.   Carpenter  enumerates  the  following  as  the  conditions 
most  desirable  for  a  module  or  apparatus  for  measuring  irrigation 
water  : 

Its  discharge  should  be  capable  of  conversion  into  the  com- 
mon measure,  which  is  cubic  feet  per  second.  The  ratio  of 
discharge  indicated  from  two  outlets  should  be  the  actual  ratio. 
The  same  module  should  give  the  same  discharge  wherever  placed  ; 


86        FLOW  AND  MEASUREMENT    IN    OPEN    CHANNELS 

it  should  be  capable  of  being  used  on  canals  of  all  sizes,  and  of 
being  set  to  discharge  any  fraction  of  its  capacity  for  the  process 
of  distributing  pro  rata.  Attempts  to  tamper  with  or  alter  its 
discharge  should  leave  traces  easy  to  recognize;  and  it  should  be 


FiG.  9. — Foote's  Measuring  W  eir,  A.     Water  Divisor,  B. 

simple  enough  to  be  operated  by  men  of  ordinary  intelligence,  so 
that  calculations  should  not  be  required  to  regulate  the  discharge 
of  different  modules  or  to  determine  the  amount  thereof.  It 
should  occupy  but  small  space,  and  the  discharge  should  not  be 
affected  by  variations  of  the  water-level  in  the  supplying  canal. 
It  should  be  inexpensive,  and  cause  the  least  possible  loss  of  head. 
Nearly  all  modules  attempt  to  maintain  a  constant  pressure  of 
water  above  the  opening,  the  orifice  remaining  unchanged. 

98.  Methods  of  Measurement. — In  Italy  and  in  some  other 
portions  of  Southern  Europe  a  "  module"  or  measuring  apparatus 
has  been  employed  with  some  success  for  the  measurement  of 


METHODS     OF    MEASUREMENT  87 

canal  water.  This  module  consists  essentially  of  inserting  in 
the  canal  bank  a  regulating  gate  on  which  the  height  of  head  can 
be  maintained.  The  size  of  the  orifice  being  known,  the  amount 
of  water  passing  through  it  can  be  at  any  time  ascertained.  Mod- 
ifications of  this  module  are  employed  to  a  limited  extent  in  India 
and  to  a  greater  extent  in  the  United  States.  The  unit  of  measure 
commonly  employed  in  America  and  Italy  is  the  "miner's"  or 
statute  inch,  though  the  second-foot  is  replacing  it.  In  India 
the  amount  of  water  flowing  in  canals  and  distributaries  is  meas- 
ured either  by  a  gauge  rod  placed  in  some  smooth  portion  of  the 
channel,  as  in  a  masonry-lined  aqueduct,  while  floats  are  timed 
for  a  given  length  in  the  aqueduct;  or  by  means  of  a  V-shaped 
measuring  weir. 

In  the  West  the  ordinary  module  employed  for  measuring 
the  miner's  inch  is  a  box  flume  closed  by  a  lifting  gate,  in  which 
case  the  head  above  the  orifice  is  changeable  and  the  amount 
passing  through  is  indeterminate.  Sometimes  a  modification  of 
this  module  devised  by  Mr.  A.  D.  Foote  is  used,  whereby  the  head 
over  the  orifice  can  be  maintained  with  some  degree  of  certainty. 
(Fig.  9.)  None  of  these  modules  is  satisfactory,  however,  for 
the  measurement  of  large  volumes  of  water.  The  measuring 
weir  is  in  all  probability  the 
most  satisfactory  method  yet 
devised  of  obtaining  an  ac- 
curate measure  of  the  volume 
of  water  passing  through  a 
canal. 

The  great  desideratum  in 
irrigation  is  a  simple  device 
for  reading  from  a  dial  or 
similar  recorder  the  discharge 

of  water  in  open  ditches.     A        FlG   I0     Au^tralian  water  Meter, 
modification   of    the  Venturi 

meter  furnishes  such  an  apparatus,  but  at  considerable  cost  for 
installation.  A  meter  recently  introduced  on  Australian  canals 
fulfils  the  same  purpose  less  satisfactorily  and  with  a  probable 
error  of  ij  to  2  per  cent.  This  consists  (Fig.  10)  of  a  wheel 


88         FLOW   AND    MEASUREMENT    IN    OPEN    CHANNELS 

with  radial  vanes  set  horizontally  in  a  box  in  the  bottom  of  the 
canal  and  just  below  a  stop  or  check.  The  water  passes  under 
the  latter  and  rises  through  the  wheel  which  is  caused  to  revolve 
and  record  on  a  dial  the  discharge.  The  operation  of  this  meter 
involves  a  loss  of  head  of  from  i  to  3  inches  according  to  the 
size  of  the  canal. 

99.  The   Statute  Inch  or  Module. — As  already   stated,   the 
statute  inch  is  a  variable  quantity,  depending  on  its  designation 
in  different  States.     As  an  example,  the  statute  inch  of  Colorado 
(Art.  58)  is  defined  as  follows:  An  inch-square  orifice  which  shall 
be  under  a  5 -inch  pressure,  measured  from  the  top  of  the  orifice 
to  the  surface  of  the  water,  in  a  box  set  in  the  banks  of  the  ditch. 
This  orifice  shall  in  all  cases  be  6  inches  perpendicular  inside 
measurement,  and  all  slides  closing  the  same  shall  move  horizon- 
tally, while  from  the  water  in  the  ditch  the  box  shall  have  a  descent 
greater  than  one-eighth  of  an  inch  to  the  foot. 

100.  Rating  Flumes. — Under  the  laws  of  the  State  of  Colorado 
rating  flumes  are  constructed  by  the  owners  of  private  channels 
for  the  measurement  of  the  flow  of  water,  while  the  State  Engineer 
is  directed  to  compute  the  amount  of  water  passing  through  them 
at  various  stages.     A  rating  flume  offers  a  convenient  means  of 
ascertaining  the  amount  of  water  flowing  in  laterals  and  distribu- 
taries at  various  depths.     It  consists  of  a  simple  open  flume 
which  is  placed  in  a  straight  portion  of  the  channel  a  few  hun- 
dred yards  below  its  headgate.     It  is  of  even  width  with  the 
channel,  on  the  same  grade,  and  its  sides  are  sufficiently  high  to 
carry  the  amount  of  water  likely  to  enter.     For  channels  exceed- 
ing 6  feet  in  width  an  apron  and  wings  of  one-inch  plank  are  built 
for  7  feet  above  and  below  the  flume.     The  latter  is  generally  16 
feet  in  length,  consisting  of  a  framing  of  6  by  6  scantling,  placed 
4  feet  apart  and  lined  with  one-inch  or  two-inch  plank. 

After  these  flumes  have  been  constructed  and  placed  the 
engineer  rates  them  by  means  of  a  current  meter,  and  furnishes 
the  Water  Commissioner  and  owner  of  the  private  channel  with 
a  table  showing  the  quantities  of  water  which  will  flow  through 
them  at  various  depths.  It  is  then  only  necessary  to  raise 
the  headgate  until  the  desired  depth  flows  through  the 


DIVISORS  89 

flume,  when  the  gate  may  be  locked.  The  great  difficulty  with 
this,  as  with  any  similar  device,  is  the  changeability  of  head  in 
the  main  channel  above  the  headgate,  the  fluctuation  therein 
causing  a  change  in  the  volume  passing  through  the  flume,  ne- 
cessitating a  corresponding  change  in  the  position  of  the  gate. 

1 01.  Divisors. — Another    method    of    distributing    water    to 
consumers  is  that  by  means  of  a  dividing  box,  the  object  of  which 
is  to  give  each  consumer  a  definite  portion  of  the  water  flowing 
in  the  lateral.     The  difficulty  of  dividing  the  water  into  two  or 
more  equal  parts  arises  from  the  fact  that  the  water  has  not  a 
uniform  velocity  across  the  entire  channel.     If,  therefore,  equal 
openings  be  made  across  a  channel,  those  near  the  centre  have 
the  greater  discharge.     As  a  consequence  the  use  of  a  divisor 
gives  only  approximate  results.     A  simple  form  of  divisor  is  that 
shown  in  Fig.  9,  B.   In  this  there  is  a  moveable  partition  A,  which 
can  be  slid  out  into  the  main  channel  so  as  to  give  the  amount 
of  water  required  in  the  branch.     In  order  to  maintain  an  equal 
velocity,  the  water  is  brought  to  a  state  of  approximate  rest  by 
a  weir  board  a  few  inches  in  height,  the  crest  of  which  is  sharp 
on  the  up-stream  side. 

102.  Stream  Measurement  Under  Ice. — Discharge  measure- 
ments may  be  made  in  ice-covered  streams  either  with  weir  or 
meter.     With  the  former  this  may  be  done  as  readily  as  in  open 
streams  provided  the  stream  is  kept  clear  of  ice  for  a  short  dis- 
tance above  the  weir  crest. 

In  making  current  meter  measurements  holes  are  cut  in  the 
ice  and  velocity  determinations  are  made  at  depths  of  .2  and  .8 
feet  below  the  bottom  of  the  ice.  It  has  been  found  that  the 
mean  velocity  can  be  found  at  either  of  these  depths  within  a 
small  percentage  of  error. 

103.  Works    of    Reference.      Flow    and    Measurement    of 
Water  in  Open  Channels. 

BARROWS,  H.  K.,  and  HORTON,  R.  E.  Determination  of  Stream  Flow  During 
the  Frozen  Season.  U.  S.  Geological  Survey,  Water  Supply  Paper  No.  187. 
Washington,  D.  C.,  1907. 

BAZIN,  M.  Recent  Experiments  on  the  Flow  of  Water  over  Weirs.  Translated 
by  A.  Marichal  and  J.  C.  Trautwine,  Jr.  Proc.  Engineers'  Club,  Phila- 
delphia. 


9O     FLOW    AND    MEASUREMENT    IN    OPEN    CHANNELS 

CARPENTER,  L.  G.     Measurement  and  Division  of  Water.     Bulletin  No.  27  State 

Agricultural  College.     Fort  Collins,  Col.,  1894. 
CHURCH,  IRVING,  P.     Mechanics  of  Engineering:   Fluids.     John  Wiley   &  Sons, 

New  York. 
FANNING,  J.  T.     Hydraulic  and  Water-supply  Engineering.     D.  Van  Nostrand 

&  Co.,  New  York,  1890. 
FLINN,  A.  D.,  and  DYER,  C.  W.  D.     The  Cippoletti  Trapezoidal  Weir.     Trans. 

Am.  Soc.  C.  E.,  Vol.  XXXII.     New  York,  July,  1894. 
FLYNN,  P.  J.     Irrigation  Canals  and  Other  Irrigation  Works,  and  Flow  of  Water 

in  Irrigation  Canals.     Denver,  Col.,  1892. 
GREEN,   J.   S.     Fourth  Biennial  Report  State  Engineer  of  Colorado.     Denver, 

Col.,  1889. 
HORTON,    ROBERT   E.     Weir   Experiments,    Coefficients   and    Formulas.     U.    S 

Geological  Survey,  Water  Supply  Paper  No,  200  Washington,  D    C.,  1907. 
HOYT,  J.  C.,  and  GROVER,  N.  C.     River  Discharge.     John  Wiley  &  Sons.     New 

York,  1907. 
JOHNSON,  J.  B.     Theory  and  Practice  of  Surveying.     John  Wiley  &  Sons,  New 

York,  1888. 
MULLINS,  Lieut.-Gen.  J.     Irrigation  Manual.     E.  &  F.  N.  Spon,   New  York, 

1890. 
MURPHY,  E.  C.     Accuracy  of  Stream  Measurements.     U.  S.  Geological  Survey, 

Water  Supply  Paper  No.  94.     Washington,  D.  C.,  1904. 
MURPHY,  E.  C.,  HOYT,  J.  C.,  and  HOLLISTER,  G.  B.     Hydrographic  Manual, 

U.  S.  Geological  Survey,  Washington,  D.  C.,  1904. 

NEWELL,  F.  H.     Part  II,  nth  and  i3th  Annual  Reports  U.  S.  Geological  Sur- 
vey, Washington,  D.  C.,  1890  and  1892. 
TRAUTWINE,   JOHN  C.     Engineers'   Pocket  Book.     John  Wiley    &  Sons,  New 

York,  1890. 
WEISBACH,  P.   J.     Hydraulics  and  Hydraulic  Motors.     Translated  and  Edited 

by  A.  Jay  Du  Bois.     John  Wiley  &  Sons,  New  York,  1891. 


CHAPTER  VII 

SUBSURFACE-WATER    SOURCES    AND    SEWAGE    FOR    IRRIGATION 

104.  Sources  of  Earth  Waters. — The  water  which  enters  the 
earth  by  percolation  either  from  rain  or  from  canals,  reservoirs, 
or  lakes  finds  its  way  through  the  soil  to  some  lower  level  where 
favorable  geologic  structure  enables  it  to  again  reach  the  surface. 
This  seepage  water  may  move  slowly  through  the  particles  of 
subsoil,  its  motion  being  rather  that  due  to  absorption  or  capillary 
attraction  than  to  direct  percolation ;  or  it  may  enter  some  seam 
between  two  formations  from  which  it  may  find  an  exit  perhaps 
at  some  great  distance  through  a  spring  or  artesian  well.     The 
flow  of  water  by  percolation  is  limited  not  only  by  the  degree  of 
porosity  of  the  strata,  but  by  their  inclination.     Yet  compara- 
tively  impervious   rocks  frequently  furnish  abundant   supplies 
which  are  the  result  of  capillary  attraction. 

105.  Motion   of   Ground   Water. — Rain-water   in   its   down- 
ward motion  through  the  soil  ultimately  reaches  a  level  which  is 
comparatively   saturated.     The  surface  of   this   zone   is   called 
the  water  table,  and  varies  greatly  in  depth  below  the  ground 
surface  in  different  localities.     The  amount  of  this  ground  water 
is  so  great  that  it  has  been  estimated  as  sufficient  to  cover  the 
surface  of  the  earth  to  a  depth  exceeding  3000  feet  and  equal 
in   total  volume  to  one-third  that  of  the  ocean  water  of  the 
globe. 

This  ground  water  is  in  continuous  though  exceedingly  slow 
motion,  and  this  is  true  not  only  in  porous  sands  but  in  even  the 
hardest  rocks.  It  is  known  also  that  this  ground  or  seepage 
water  flows  more  freely  at  high  than  at  low  temperatures.  At 
a  mean  depth  of  6  feet  below  the  surface  perhaps  one-third  more 
water  will  flow  in  sand  in  the  warmest  than  in  the  coldest  part 
of  the  year.  Among  the  most  important  conclusions  on  this 

91 


92  SUBSURFACE-WATER    SOURCES    AND     SEWAGE 

subject  are  those  of  Mr.  Allen  Hazen,  which  for  closely  packed 
sand  saturated  with  water  are  expressed  in  the  formula 

h  //Fahr.+  10 


where  v  is  the  velocity  of  the  water  in  meters  daily  in  a  solid 
column  of  the  same  area  as  that  of  the  sand,  or  ap- 
proximately in  million  gallons  per  acre  daily; 

c  is  a  constant  factor  which  present  experiments  indicate 
to  be  approximately  1000; 

d  is  the  effective  size  of  sand  grain  in  millimeters  ; 

h  is  the  loss  of  head  ; 

/  is  the  thickness  of  sand  through  which  the  water  passes  ; 

t  is  the  temperature  (Fahr.). 

The  formula  can  only  be  used  for  sands  with  coefficients 
below  5  and  effective  sizes  from  o.i  to  3.0  mm.,  and  with  the 
coarser  materials  only  for  moderately  low  rates. 

Mr.  Hazen  publishes  a  table  in  his  book  showing  the  rela- 
tive quantities  of  water  at  different  temperatures  which  passed 
through  experimental  filters.  Taking  as  unity  the  quantity 
passing  at  50°  F.,  0.70  passed  at  32°  and  1.35  at  71°;  or  for  every 
three  degrees  increase  in  temperature  the  quantity  of  water 
passing  increased  by  5%.  In  the  above  the  effective  size  is 
the  size  of  grain  such  that  10%  by  weight  of  the  particles  are 
smaller  than  this.  The  uniformity  coefficient  is  the  ratio  of 
the  size  of  grain  which  has  60%  of  the  sample  finer  than  itself  to 
the  size  of  which  has  10%  finer  than  itself. 

An  idea  of  the  slowness  of  flow  of  ground  water  may  be  had 
from  the  studies  of  Mr.  N.  H.  Darton,  who  places  the  rate  of 
motion  in  the  sands  of  the  Dakota  formation  at  a  mile  or  two 
a  year.  A  French  engineer  gives  the  same  rate,  or  an  eighth 
of  an  inch  a  minute.  In  Arizona  a  rate  of  one-fourth  of  an  inch 
a  minute,  and  in  Kansas  three-eighths  inch  a  minute,  have  been 
estimated  (Art.  120).  At  Agua  Fria,  Arizona,  the  measured 
rate  of  flow  of  ground  water  in  creek  gravels  having  28% 
voids  was  4  feet  a  day.  As  a  result  of  careful  investigation, 
Mr.  C.  S.  Slichter  gives  the  rate  of  flow  for  a  grade  of  10  feet 
per  mile  as  follows  : 


j         UNDERFLOW  93 

Material.  Velocity,  Miles.  Per  Annum,  Feet. 

Fine  sand o.oi  52.8 

Medium  sand 0.04  216.0 

Coarse  sand o.  16  845 .o 

Fine  gravel 1.02  5386.0 

1 06.  Underflow. — This  word  has  been  improperly  used  to 
designate  a  supposed  vast  sheet  of  water  flowing  eastward  under 
the  slopes  of  the  great  plains  from  the  Rocky  Mountains.     It  is 
otherwise  and  properly  used  by  Slichter  to  describe  the  water 
moving  in  a  thalweg  or  valley  bottom  beneath  the  gravelly  bed 
of  a  watercourse.     Though  such  underflow  may  not  be  possible 
in  the  fine  silt  and  sand  forming  the  beds  of  some  streams,  it  may 
be  of  appreciable  amount  as  stored  water  in  coarser  sands  and 
gravels.     The  amount  and  rate  of  underflow  vary  greatly  with  the 
source  of  seepage  water,  the  nature  of  the  material  and  the  slope. 
In  the  Hondo  and  San  Gabriel  rivers,  California,  the  rate  of 
movement  of  underflow  has  been  determined  to  be  from  3^  to 
5  and  7  feet  per  day.     Velocities  of  flow  through  the  bed  of  the 
Fresno  canal,  California,  of  1.6  feet  to  4.8  feet  a  day,  have  been 
measured.     At  the  Weldon  valley  canal,  Colorado,  velocities  of 
underflow  of   1600  feet  a  year  have  been  observed.     On  the 
Mojave  River,  California,  underflow  velocities  of  6,  20,  35,  48, 
and  64  feet  per  day  were  measured  at  various  points.     In  con- 
clusion it  may  be  stated  that  the  velocity  of  underflow  is  very 
small  and  the  total  amount  is  generally  insignificant  as  a  source 
of  water  supply  for  irrigation.     The  velocity  is  especially  small 
in  the  beds  of  silt-laden  streams,  though  the  quantity  of  under- 
flow water  may  be  correspondingly  great. 

107.  Sources   of   Springs   and    Artesian    Wells. — Wells    and 
springs  usually  derive  their  water  supplies  from  shallow  forma- 
tions as  gravels,  sands,  and  marls.     Their  temperature  may  be 
variable  owing  to  the  changes  in  the  temperature  of  the  surface 
of  the  soil,  while  their  flow  is  affected  by  precipitation  of  recent 
occurrence  and  by  evaporation  from  the  surface  of  the  ground. 

Gravitation  tends  to  draw  the  water  toward  the  centre  of 
the  earth,  and  it  percolates  in  that  direction  until  intercepted 
by  some  impervious  stratum  along  which  it  finds  its  way.  If 
the  water  fills  a  pervious  stratum  so  surrounded  by  impervious 


94  SUBSURFACE-WATER    SOURCES    AND     SEWAGE 

strata  that  it  is  prevented  from  escaping,  and  the  hydrostatic 
pressure  due  to  the  inclination  of  the  beds  is  sufficient  to  bring 
the  water  to  the  surface,  the  conditions  are  favorable  for  the 
production  of  an  artesian  well.  All  that  is  necessary  is  to  pierce 
the  upper  confining  stratum  by  boring,  when  the  water  will 
escape.  Generally  artesian  supplies  exist  in  the  newer  sand- 
stones and  other  equally  porous  rocks.  Waters  are  frequently 
gathered  into  such  strata  from  distant  catchment  basins.  Where 
such  a  water-bearing  stratum  approaches  the  surface  in  a  broad 
plain  it  forms  an  extensive  artesian  basin. 

108.  Artesian  Wells. — Deep  wells  do  not  always  overflow. 
The  condition  of  overflow  depends  on  whether  the  pressure  is 
sufficiently  great  to  force  the  water  above  the  surface,  in  which 
case  they  are  known  as  artesian  wells.     Frequently  the  water 
will  reach  within  but  a  few  feet  of  the  surface,  when  an  ordi- 
nary well  or  shaft  can  be  excavated  and  the 'water  pumped  to 
the  desired  height.     In  many  other  cases  the  pressure  is  such  that 
the  water  spouts  forth  from  the  well  under  considerable  pressure 
to  great  heights.     In  an  artesian  area  of  considerable  extent 
the  various  wells  seriously  influence  each  other.     In  the  San 
Gabriel  and  San  Bernardino  valleys  in  Southern  California  it  has 
been  found  that  after  a  certain  number  of  wells  have  been  sunk 
each  additional  well  affects  its  neighbors  by  diminishing  their 
discharge.     There  thus  comes  a  point  in  the  sinking  of  wells 
when  the  number  which  can  be  utilized  in  any  given  area  or 
basin  is  limited. 

109.  Examples  of  Artesian  Wells. — Some  great  wells  have 
been  sunk  in  different  parts  of  the  world.    The  celebrated  Grinnell 
well  in  Paris  commenced  with  a  20-inch  bore  and  is  gradually 
reduced  to  an  8-inch  bore  at  the  bottom;   its  depth  is  1806  feet, 
and  its  yield  has  been  as  great  as  1.5  second-feet.     A  well  has 
recently  been  bored   in  the  neighborhood  of   Wheeling,   West 
Virginia,  to  the  great  depth  of  4500  feet,  but  is  dry.     At  Speren- 
berg,  near  Berlin,  is  a  well  4170  feet  deep,  and  at  Schladabach, 
near  Leipsic,  is  a  well  5740  feet  in  depth.     In  St.  Louis  is  a  well 
which  reaches  a  depth  of  3850  feet,  about  3000  feet  below  the  sea- 
level.     In  San  Bernardino  and  San  Gabriel  valley  in  Southern 


CAPACITY  AND  COST  OF  ARTESIAN  WELLS      95 

California  and  in  the  upper  San  Joaquin  valley  in  the  neighborhood 
of  Bakersfield  are  some  very  extensive  artesian  areas,  but  the 
greatest  artesian  basins  of  the  West  are  found  in  the  neighborhood 
of  Waco,  Texas;  Denver,  Colorado;  and  the  James  River  valley 
and  the  neighborhood  of  Huron  in  the  Dakotas. 

In  1890  there  were  8097  artesian  wells  on  farms  in  the  arid 
region.  Of  these  32.110  were  in  California,  2,524  in  Utah,  596  in 
Colorado,  and  between  460  and  527  respectively  in  North  Dakota 
and  South  Dakota,  and  534  in  Texas,  besides  a  few  in  each  of 
the  remaining  States  and  Territories.  Of  these  wells  48^  per 
cent  were  used  in  irrigating  51,896  acres  at  the  average  rate  of 
13.2  acres  per  well.  Their  average  depth  is  210  feet,  average 
cost  $245,  and  average  discharge  0.12  second-feet. 

no.  Capacity  and  Cost  of  Artesian  Wells. — The  capacities 
of  flowing  wells  are  relatively  small  as  compared  with  the  volumes 
of  water  required  in  irrigation.  Of  the  eight  thousand  wells 
reported  from  the  arid  region  comparatively  few  are  of  sufficient 
capacity  for  use  in  irrigation.  The  great  majority  are  shallow  in 
depth  and  small  in  bore  and  discharge.  They  range  from  100 
to  200  feet  in  depth,  from  2  to  4  inches  in  internal  diameter,  and 
discharge  rarely  as  much  as  o.i  of  a  second-foot;  though  this 
volume,  if  stored  in  a  suitably  located  reservoir,  should  irrigate 
a  moderate-sized  farm.  On  the  other  hand  there  are,  especially 
in  South  Dakota  and  Southern  California,  some  very  large  flow- 
ing wells.  In  the  former  State  there  are  reported  to  be  at  least 
twenty-five  wells  with  discharges  ranging  from  i  to  6  second-feet, 
and  in  Southern  California  about  thirty  Wells  of  similar  capacities. 
The  largest  well  in  South  Dakota  delivers  continuously  about 
6.68  second-feet. 

The  cost  of  sinking  artesian  wells  is  an  exceedingly  variable 
quantity,  and  is  dependent  upon  the  depth  and  bore  of  the  well 
and  the  material  through  which  it  is  sunk.  In  some  localities, 
under  favorable  conditions,  6-inch  wells  of  moderate  depth  are 
sunk  and  lined  at  prices  ranging  between  $2.75  and  $3.50  per  foot. 
In  North  Dakota,  where  wells  are  sunk  through  sandstone,  wells 
of  2  to  4  inches  diameter  are  sunk  for  about  80  cents  for  the  first 
hundred  feet  up  to  $1.50  for  the  second  hundred  feet.  One  well 


96  SUBSURFACE-WATER    SOURCES    AND    SEWAGE 

1084  feet  in  depth  cost  $4000  and  yields  4  second-feet.  In  South 
Dakota  are  many  2 -inch  wells  of  depths  from  250  to  300  feet, 
which  have  been  sunk  at  the  very  low  price  of  $75,  the  price  in- 
creasing thence  to  $300  for  a  3-inch  well  300  feet  deep.  In  other 
places,  where  more  gravel  and  stone  are  encountered,  2 -inch  wells 
have  cost  $300,  and  3-  and  4-inch  wells  from  $400  to  $1000. 
One  well  850  feet  in  depth,  4  inches  in  diameter,  cost  $1800,  and 
discharges  3  second-feet,  irrigating  about  100  acres.  In  Colorado 
in  sandstone  and  hard  clay  the  cost  of  well-drilling  averages 
$2  per  foot. 

in.  Storage  of  Artesian  Water. — Having  decided,  from  a 
study  of  the  geology  and  a  knowledge  of  the  success  attained  by 
other  wells,  the  general  locality  in  which  the  well  is  to  be  drilled, 
its  specific  location  should  if  possible  be  on  the  highest  point  of 
the  land  to  be  irrigated,  and  in  such  a  position  that  it  may  be 
outside  of  and  tributary  to  the  reservoir  in  which  the  water  is  to  be 
stored.  Since  artesian  wells  flow  continuously  during  twenty- 
four  hours  of  the  day  and  three  hundred  and  sixty- five  days  in 
the  year,  it  is  desirable  to  store  as  much  of  the  water  which  flows 
during  the  non-irrigating  period  as  possible,  in  order  that  the 
greatest  duty  may  be  gotten  from  the  well.  The  volume  flowing 
continuously  from  almost  any  well  is  usually  too  small  to  enable 
it  to  flow  over  the  land  in  sufficient  volume  for  the  purposes  of 
irrigation,  so  that  a  necessary  adjunct  to  nearly  every  well  is  a 
storage  reservoir  of  greater  or  less  dimensions.  In  the  case,  how- 
ever, of  a  well  which  discharges  about  i  second-foot,  or  nearly 
enough  to  irrigate  100  acres  from  unstored  flow,  such  a  well  may 
be  made  capable  of  irrigating  ten  times  this  area  if  the  water  flow- 
ing at  other  times  than  the  irrigating  periods  can  be  stored.  Small 
reservoirs,  sufficiently  large  to  retain  only  enough  water  to  pro- 
duce the  requisite  head  for  flowing  over,  may  be  built  as  are 
watering-tanks  on  railways,  or  they  may  be  cheaply  excavated 
in  the  highest  ground  on  the  farm  and  properly  lined.  Larger 
ones  may  be  constructed  by  making  use  of  the  natural  configura- 
tion of  the  country  and  building  a  dam  across  a  hollow  or  ravine. 
(Chap.  XV.) 

112.  Size  of  Well. — The  volume  of  the  well  does  not  depend 


MANNER   OF   HAVING   WELLS   DRILLED  97 

upon  its  size.  A  6-inch  well  will  not  necessarily  discharge  twice 
as  much  water  as  a  3-inch  well — perhaps  not  as  much.  The 
amount  of  flow  depends  directly  upon  the  volume  of  the  water- 
bearing strata  and  the  pressure  due  to  its  initial  head  or  source. 
Providing  this  is  sufficiently  great,  then  the  discharge  of  the  well 
is  dependent  on  its  diameter.  Other  things  being  equal,  a  large 
well  will  cost  more  to  drill,  but  will  be  more  easily  and  cheaply 
cleaned  and  kept  in  operation  than  a  smaller  one,  which  is  apt  to 
clog.  Further,  during  and  after  drilling  an  accident  may  ruin  a 
small  well,  while  a  larger  one  may  be  recased  with  diminished  bore 
and  still  remain  serviceable.  For  purposes  of  irrigation  it  may 
in  general  be  said  that  a  well  less  than  4  inches  in  diameter  should 
not  be  drilled,  and  it  is  probable  that  one  with  a  bottom  bore 
greater  than  8  inches  will  not  be  economical. 

Nearly  all  wells  which  terminate  in  soft  rock,  sand,  or  gravel 
discharge  more  or  less  of  these  materials.  To  prevent  this  from 
clogging  the  well  it  is  not  uncommon  to  place  perforated  pipe  in 
the  bottom  of  the  well  through  the  water-bearing  stratum.  There 
are  many  styles  of  such  pipe,  but  in  general  it  may  be  stated  that 
pipe  with  circular  perforations  of  uniform  diameter  is  not  the 
most  serviceable,  as  it  is  apt  to  become  clogged.  Some  of  the 
patented  perforated  pipes  with  slots  having  less  aperture  on  the 
outer  than  on  the  inner  surface  are  preferable.  In  some  cases  ex- 
perience may  show  that  it  is  not  desirable  to  insert  perforated 
pipe,  but  to  let  whatever  comes  to  the  well  be  discharged  and  col- 
lected in  the  storage  reservoir. 

113.  Manner  of  Having  Wells  Drilled. — There  are  many 
responsible  firms  who  make  a  business  of  drilling  and  boring 
artesian  wells,  and  for  those  who  are  unfamiliar  with  the  business 
of  well-sinking  it  is  better  to  contract  with  some  such  firm  to 
perform  the  work  required.  On  the  other  hand,  the  sinking  of 
a  well  is  not  a  difficult  operation  for  those  who  have  any  idea  of 
the  process,  though  by  contracting  they  are  certain  of  having 
the  well  sunk  as  they  desire,  within  a  fixed  price,  and  are  relieved 
of  the  risk  of  accidents. 

In  the  oil  and  gas  regions  the  drilling  of  wells  to  tap  oil-  and 
gas-bearing  strata,  which  is  a  process  entirely  similar  to  that 


98  SUBSURFACE-WATER    SOURCES    AND     SEWAGE 

of  drillings  wells  for  water,  is  a  matter  of  every-day  occurrence, 
and  nearly  all  who  desire  to  sink  wells  perform  the  work  on  a 
sort  of  half-contract  system.  The  principal  apparatus  com- 
prises an  engine,  boiler,  carpenter's  rig,  and  set  of  drilling-tools, 
and  the  common  practice  is  for  the  owner  to  provide  all  except 
the  tools  and  fuel  and  let  the  drilling  of  the  well  at  so  much  a 
foot  to  a  contractor  who  furnishes  these  and  does  the  work  of 
putting  down  the  well.  In  Ohio  and  Pennsylvania  wells  drilled 
in  this  manner  by  half-contract  cost  from  50  to  80  cents  per 
foot  for  moderate-sized  wells  up  to  $1.50  to  $2  for  large  and 
deep  wells. 

114.  Varieties  of  Drilling-machines. — Wells  may  be  drilled 
by  various  methods,  among  the  chief  of  which  are  by  cables, 
poles,  and  hydraulic  process.  Provided  the  well  is  to  be  drilled 
by  contract,  it  is  of  little  importance  what  method  is  employed, 
since  the  contractor  is  responsible  for  the  proper  completion 
of  the  work,  and  the  style  of  rig  is  a  matter  for  his  own  choice. 
In  the  Dakotas  and  some  other  of  the  plains  regions  it  has  been 
found  that  wells  drilled  with  pole  machines  have  proved  most 
satisfactory  and  performed  the  cheapest  work,  aside  from  the 
amount  of  time  taken  in  coupling  and  uncoupling  the  rods.  In 
the  oil-and  gas-bearing  regions  cable  machines  are  most  popular. 
There  are  many  patterns  of  hydraulic,  jetting,  and  rotary  rigs 
which  are  adopted  by  different  well-boring  firms.  The  latter 
are  dependent  upon  a  rotary  motion  given  to  a  piston-rod  working 
by  hy'draulic  power  and  turning  a  tubing  with  cutting  edge.  In 
hydraulic  jetting  machines,  which  can  be  used  cheaply  only  in 
gravel  or  sand,  there  is  employed  a  short  drill-bit  having  a  hollow 
shank  through  which  a  jet  of  water  is  forced  from  pipe  rods, 
thus  creating  an  upward  current  which  carries  out  the  drillings. 
Some  of  these  hydraulic  and  jetting  machines  have  met  with 
remarkable  success. 

The  chief  advantage  of  pole  rigs  over  cable  rigs  is  in  the 
certainty  of  the  revolutions  given  to  the  drill,  as  the  rods  form 
a  rigid  connection  between  the  drill  and  the  machine  above, 
and  the  motion  is  uniform  in  the  direction  of  tightening  the 
screws  of  the  joints.  This  tends  to  preserve  the  connection, 


VARIETIES     OF    DRILLING-MACHINES  99 

and  keep  the  drill  under  perfect  control.  Cable  rigs  are  chiefly 
preferred  because  of  the  ease  with  which  they  can  be  operated 
and  the  speed  with  which  the  tools  can  be  lowered  and  removed 
and  the  bailing  apparatus  substituted  in  their  place.  The  chief 
disadvantages  as  compared  with  the  pole  rigs  is  in  the  greater 
friction  produced  by  the  corrugated  surface  of  the  cable,  the 
uncertainty  as  to  whether  the  striking  bar  reaches  the  bottom 
of  the  drill,  the  likelihood  of  cutting  or  bending  the  cable,  and 


FIG.  ii. — Portable  Artesian-well  Drilling  Rig. 

the  danger  of  breaking  under  the  strain  when  tools  become  fast. 
As  the  cable  is  rotated  both  to  the  right  and  left  there  is  also 
liability  of  uncoupling  the  joints  at  the  tools,  and  there  is  a  pos- 
sibility that  the  cable  may  not  produce  the  proper  rotation  in 
the  drill,  and  thus  not  bore  the  hole  truly  circular.  There  are 
now  on  the  market  a  number  of  excellent  portable  well-drilling 
rigs,  both  of  the  old  reliable  walking-beam  type  (Fig.  n),  and 
also  jetting  and  hydraulic  rotary  rigs.  These  can  frequently 


100          SUBSURFACE- WATER    SOURCES    AND    SEWAGE 

be  purchased  outright  at  prices  which  will  render  them  cheaper 
than  any  other  method  of  having  wells  drilled. 

115.  Process  of  Drilling. — The  general  process  of  drilling 
consists  in  having  a  long,  heavy  drilling-bar,  the  lower  end  of 
which  is  dressed  to  a  cutting  edge,  which  is  dropped  into  a  hole 
in  the  rock  and  by  its  weight  cuts  or  breaks  the  stone  where  it 
strikes.  At  each  blow  this  rod  is  turned  a  little,  thus  making 
the  hole  round.  The  drill  is  hung  from  the  end  of  a  cable  or 
series  of  jointed  poles  which  are  raised  and  dropped  by  machinery. 
After  the  drill  has  worked  for  a  short  time  it  is  removed,  and 
the  drillings,  or  small  pieces  of  rock  which  have  collected  in  the 
bottom  of  the  hole  and  deaden  the  blow  of  the  drill,  are  removed. 
This  is  done  by  pouring  water  in  the  hole  if  it  be  dry,  and  the 
fluid  mud  thus  formed  is  lifted  to  the  surface  by  a  long,  narrow 
bailer  with  a  valve  at  its  lower  end.  These  operations  of  drilling 
from  three  to  five  feet,  then  cleaning  out  the  mud  and  drilling 
again,  are  alternated  until  the  desired  depth  is  reached.  If  casing 
or  lining  is  to  be  introduced  and  the  hole  is  not  drilled  truly 
cylindrical,  it  is  reamed  out  by  a  steel  tool  of  desired  diameter, 
weighing  about  125  pounds  and  attached  in  place  of  the  drill. 

The  apparatus  which  goes  to  make  a  drilling-machine  com- 
prises an  engine  and  boiler  of  about  20  horse-power,  a  set  of 
drilling-tools,  and  cable  or  poles.  These  latter  are  generally 
spoken  of  as  the  rig.  It  is  also  necessary  to  provide  tubing  or 
casing  to  line  the  well  through  such  permeable  strata  as  might 
cause  the  loss  of  water  or  through  such  strata  as  may  provide 
water  which  is  undesirable  for  the  purposes  required.  It  is  some- 
times necessary  to  line  wells  with  tubing  throughout  their  entire 
length,  and  in  such  cases  it  is  usual  to  begin  with  a  large  bore,  say 
8  inches,  and  after  sinking  this  to  a  given  depth,  say  200  or  300 
feet,  to  reduce  the  diameter  of  the  tubing  by  an  inch  or  two. 

The  "set  of  tools"  which  compose  the  drill — for  the  latter 
is  not  a  solid  bar,  but  several  pieces — weigh  about  2500  pounds, 
and  consist  of  a  steel  "bit"  or  "drill,"  of  the  size  of  the  bore 
desired,  screwed  into  the  lower  end  of  the  "auger  stem,"  which 
latter  is  a  steel  rod  30  feet  long  and  3  inches  in  diameter.  To 
the  upper  end  of  this  are  screwed  "jars,"  and  above  them  the 


PROCESS     OF     DRILLING  IOI 

''sinker-bar,"  which  is  15  feet  long  and  3  inches  in  diameter, 
and  of  steel.  The  jars  by  slacking  together  in  falling  cause  the 
sinker-bar  to  act  on  and  through  them  to  the  drill  as  a  hammer. 
The  term  "rig"  generally  includes,  in  addition  to  the  set  of  tools, 
the  woodwork  and  necessary  iron  fittings  forming  a  derrick  to 
carry  a  sheave  at  a  sufficient  height,  perhaps  50  to  80  feet,  to 
swing  the  drilling-tools  clear  of  the  ground;  also,  both  wheels 
and  shaft  on  which  the  drill  cable  is  wound;  the  sand-reel  for 
winding  up  the  smaller  rope  used  in  cleaning  out  the  drillings; 
a  walking-beam  to  give  vertical  motion,  and  a  band- wheel  for 
transmitting  power  from  the  engine  to  the  moving  parts. 

After  the  engine  has  been  started  and  the  walking-beam  is 
made  to  rock  up  and  down  at  the  rate  of  20  to  30  strokes  a  minute, 
lifting  the  tools  with  it,  the  length  of  stroke  being  adjustable 
from  15  inches  to  3  feet,  the  rope  is  then  twisted  by  means  of  a 
stick,  first  in  one  direction  for  a  while  and  then  in  the  opposite 
direction  alternately.  This  twisting  of  the  rope  turns  the  drill, 
and  the  driller  who  handles  the  rope  knows  by  the  "feel"  how 
the  tools  are  working,  the  texture  of  the  rock,  and  the  occurrence 
of  an  accident.  Occasionally  the  temper  and  set-screws  are 
turned  out  a  little,  thus  lowering  the  tools.  After  the  drilling 
has  gone  on  to  a  depth  of  4  or  5  feet  the  tools  are  hoisted  clear 
of  the  floor,  the  bull-rope  swung  off  to  one  side,  and  the  bailer 
or  sand -pump  is  swung  over  the  hold  from  the  sand-reel,  and 
is  allowed  to  drop  by  its  own  weight,  and  upon  reaching  the 
bottom  is  filled  with  mud  and  sand  through  the  valve  at  its  lower 
end  and  is  then  drawn  up  and  emptied;  this  process  being  re- 
peated if  necessary  to  clear  the  hole  before  drilling  is  again  re- 
sumed. The  rate  of  drilling  depends  wholly  upon  the  character 
of  strata  encountered,  but  averages  from  15  to  50  feet  per  working 
day. 

A  method  of  deep-well  construction  employed  in  California 
and  known  as  the  stovepipe  method  is  admirably  adapted  to 
conditions  where  the  material  to  be  drilled  consists  of  coarse 
debris.  Casing  from  10  to  14  inches  in  diameter  is  put  down, 
reaching  in  one  instance  to  1300  feet  in  depth.  A  starter  is  used 
consisting  of  a  length  of  15  to  25  feet  of  No.  10  riveted  sheet  steel 


102  SUBSURFACE-WATER    SOURCES    AND    SEWAGE 

with  a  sharpened  steel  shoe.  The  remainder  of  the  casing  above 
is  of  No.  12  sheet  steel  in  lengths  of  only  two'feet,  each  following 
section  being  smaller  than  the  last  so  as  snugly  to  telescope  for 
one  foot  of  length,  thus  forming  a  double  shell  of  stovepipe  casing. 
This  is  sunk  by  the  ordinary  oil-well  type  of  machinery,  the  casing 
being  forced  down,  however,  by  hydraulic  jacks.  After  the  well  is 
sunk  a  cutting- knife  is  lowered  into  it  and  vertical  slits  are  cut 
in  the  casing  opposite  water-bearing  strata. 

The  advantages  of  these  methods  are :  absence  of  short  fragile 
screw-joints;  flush  outer  surface  which  does  not  catch  in  clay  or 
projecting  rocks;  its  elastic  character  permits  it  to  adjust  itself 
to  obstacles  and  stresses;  its  cheapness  for  large  sizes  of  casing, 
the  short  sections  permit  the  hydraulic  jacks  to  force  it  down; 
the  ability  to  perforate  the  casing  at  any  depth  with  a  large  size 
of  perforation  inside. 

The  cost  of  such  wells  averages  about  $i  per  foot  for  casing; 
$40  for  the  starter;  and  for  the  drilling  50  cents  per  foot  for  the 
first  100  feet,  thereafter  25  cents  additional  for  each  succeeding 
50  feet. 

1 1 6.  Capacity  of  Common  Wells. — The  supplying  capacity 
of  common  wells  is  frequently  increased  considerably  by  irri- 
gation. As  water  is  applied  to  the  soil  through  a  period  of  years 
the  subsurface-water  plane  rises,  and  it  may  be  reached  at  lesser 
depths  than  previously.  In  this  way  irrigation  water  may  be 
used  over  several  times;  by  pumping  it  from  wells  it  may  find 
its  way  by  seepage  back  to  the  streams,  from  which  it  may  be 
again  diverted.  The  capacity  of  surface  or  common  wells  de- 
pends on  the  degree  of  fineness  of  the  water-bearing  stratum, 
fine-grained  material  yielding  water  more  slowly  and  of  less 
amount  than  coarser  material.  The  yield  also  depends  on  the 
head  or  depth  below  the  surface  of  the  water-table  at  which 
the  flow  takes  place;  also  upon  the  size  and  shape  of  the  exca- 
vation and  the  character  of  the  well  walls  or  casing.  The  yield 
is  directly  proportional  to  the  freedom  with  which  the  water- 
bearing material  permits  the  movement  of  water,  and  also  to  the 
head  or  depth  by  which  the  water-table  is  lowered.  Of  a  series 
of  wells  across  the  Rio  Grande  valley  near  Las  Cruces,  N.  M., 


WELLS,    POWER-PUMPED  103 

those  near  the  river,  in  fine  compact  deposits  of  the  valley  bottom, 
have  a  small  yield  compared  with  the  greater  capacity  of  wells 
some  distance  from  the  river,  under  the  mesa  foot  in  the  coarser 
mountain  debris.  If  the  well  is  shallow,  increasing  the  diameter 
increases  the  flow;  but  if  deep  and  relatively  small  in  diameter, 
as  a  pipe,  increasing  the  diameter  does  not  appreciably  increase 
the  flow.  For  the  above  reasons  driven-pipe  wells  yield  rela- 
tively more  water  than  open  dug  wells. 

The  extent  to  which  common  wells  may  be  used  as  a  source 
of  supply  for  irrigation  is  not  appreciated  in  the  United  States, 
where  as  yet  irrigation  is  practised  only  in  a  large  way  and  ir- 
rigators  are  but  just  coming  to  a  realization  of  the  advantages 
of  intensive  cultivation,  whereby  but  a  few  acres  are  worked  by  a 
single  farmer,  but  in  the  most  thorough  manner  possible.  In  a 
few  portions  of  the  Far  West,  notably  in  Central  and  Southern 
California,  where  Italians  and  Chinamen  are  engaged  chiefly 
in  market-gardening,  wells  are  employed  to  some  extent  for  the 
supply  of  water.  In  such  cases  the  water  is  raised  by  one  of 
several  processes  (Chap.  XIX),  chiefly  by  windmills,  and  by 
mechanical  lifts  worked  by  horse-power,  and  similar  to  the  Per- 
sian wheel  of  Asia. 

It  is  to  India  that  we  must  look  in  order  to  gain  an  idea  of 
the  extent  to  which  wells  may  furnish  irrigation  water.  In  the 
Central  Provinces  of  India  120,000  acres  are  irrigated  from  wells. 
In  Madras  2,000,000  acres  are  irrigated  from  400,000  wells. 
In  the  Northwest  Provinces  360,000  acres  are  irrigated  frort 
wells.  Some  of  these  wells  are  sunk  to  depths  as  great  as  80 
to  100  feet,  in  some  cases  through  hard  rock,  and  are  capable 
in  ordinary  seasons  of  irrigating  from  I  to  4  acres  each.  These 
wells  may  really  be  said  to  supplement  irrigation  from  canals 
and  reservoirs,  for  after  the  waters  of  the  latter  have  been  used 
and  have  seeped  into  the  soil  they  are  caught*  by  the  well 
and  are  again  used  for  irrigation.  Thus  wells  as  an  adjunct 
to  canals  may  be  said  to  add  materially  to  the  duty  of  the 
latter. 

117.  Wells,  Power-Pumped.— Throughout  the  West  are  now 
many  drilled  wells  which  supply  large  quantities  of  water  for 


104 


SUBSURFACE-WATER     SOURCES    AND     SEWAGE 


TUNNELLING     FOR    WATER  ^05 

irrigation  either  by  windmill  pumping  or  by  power  pumping 
with  gasoline,  steam  or  electric  motors  (Chap.  XIX). 

The  Reclamation  Service  has  just  completed  a  most  elaborate 
project  near  Garden  City,  Kan.,  for  pumping  ground  water  in 
the  Arkansas  River  valley  from  a  series  of  23  driven  wells.  Power 
is  furnished  by  two  steam  turbines  direct-connected  with  225 
kilowatt  alternators  located  near  the  middle  of  a  line  of  pumping 
plants  23,000  feet  in  length.  The  pumping  stations  are  1,000 
feet  apart  and  each  pump  draws  water  from  10  wells  drilled  in  the 
gravel  to  a  depth  of  8  to  12  feet  (Fig.  12).  At  present  there  are 
in  operation  ten  p-inch  centrifugal  pumps  of  5  second-feet  capacity 
each  operated  by  25  horse-power  motors  and  thirteen  io-inch 
centrifugal  pumps  of  similar  capacity  and  power,  all  discharging 
into  a  concrete-lined  conduit  which  empties  into  12  miles  of  ditch. 

118.  Tunnelling  for  Water. — Tunnels  are  sometimes  driven 
in  sloping  or  sidehill  country  to  tap  the  subterranean  water- 
supplies.  These  are  practically  horizontal  wells,  differing  from 
ordinary  wells  chiefly  in  that  the  water  has  not  to  be  (dumped 
to  bring  it  to  the  level  of  the  surface,  but  finds  its  way  by  gravity 
flow  to  the  lands  on  which  it  is  to  be  utilized.  Near  the  Khojak 
Pass  in  India  is  a  great  tunnel  of  this  kind.  This  is  run  near  the 
dry  bed  of  a  stream  into  the  gravels  for  a  distance  of  over  a  mile. 
The  slope  of  its  bed  is  3  in  1000,  its  cross-section  is  1.7X3  feet, 
and  its  discharge  about  9  second-feet.  The  Ontario  Colony 
in  Southern  California  derive  their  water-supply  from  a  tunnel 
3300  feet  in  length,  run  under  the  bed  of  San  Antonio  creek 
through  gravel  and  rock.  Its  cross-section  is  5  feet  6  inches 
high,  3  feet  6  inches  wide  at  bottom,  and  2  feet  wide  at  top.  It 
is  partly  timbered  and  partly  lined  with  concrete,  having  weep- 
holes  in  the  upper  part  of  the  tunnel.  Its  discharge  is  about 
6  second-feet.  The  supply  from  several  subtunnels  has  been 
such  as  to  average  nearly  10  second -feet  per  linear  mile  of  tunnel. 

The  Spring  Valley  Water  Company  which  supplies  San 
Francisco,  California,  has  recently  made  some  of  the  most  ex- 
tensive developments  of  water  from  subsurface  sources  yet 
recorded.  One  bed  of  gravel  in  a  stream  valley  having  an  area 
of  1200  acres  absorbs  practically  all  the  drainage  of  300  square 


io6 


SUB  SURF  ACE- WATER     SOURCES     AND     SEWAGE 


miles.  Into  these  gravels  were  sunk  91  wells  which  yield  36 
acre-feet  of  water  per  day.  Another  similar  bed  has  been  de- 
veloped by  drifting  over  14,000  feet  of  tunnel  5'  6"X$'  6",  with 
nearly  as  great  a  length  of  smaller  branch  tunnel.  Into  this 
drain  several  hundred  driven  wells  (Fig.  13)  which  yield  over 
45  acre-feet  of  water  per  day. 

119.  Underground  Cribwork. — Submerged  cribs  were  planned 
for  the  American  Water  Company  on  Cherry  Creek  in  Colorado, 
and  have  been  used  by  the  Citizens'  Water  Company  on  the 


FIG.  13. — Subterranean  Water  Tunnel  and  Feed-wells,  California. 

South  Fork  of  the  Platte  River  in  Colorado.  The  former  enter- 
prise contemplated  a  submerged  open  crib  sunk  in  the  gravel 
bed  of  Cherry  Creek,  and  resting  on  blue  clay  which  is  73  feet 
below  the  surface  of  the  stream,  rising  to  a  height  of  70  feet, 
with  its  crest  3  feet  below  the  bed  of  the  stream.  This  was  not  to 
be  a  dam,  but  to  stop  the  movement  of  that  portion  of  the  sub- 
surface water  which  might  enter  the  cribwork.  It  would  consist 
of  timbers  14  inches  in  dimension  at  the  bottom,  decreased  to  8 
inches  at  the  top,  placed  4  feet  apart  across  stream,  and  planked 


OTHER    SUBSURFACE-WATER   SOURCES  107 

on  both  faces  with  interstices  of  3  inches  on  the  upper  face. 
The  water  caught  in  this  crib  work  was  to  be  pumped  to  the  surf  ace. 
The  Citizens'  Water  Company  develops  the  underground 
waters  of  the  Platte  River  by  means  of  a  series  of  gathering-gal- 
leries, consisting  of  perforated  pipe  and  open  cribwork  laid  at 
a  depth  of  from  14  to  22  feet  below  the  surface  of  the  gravel  bed 
of  the  stream.  The  cribs  (Fig.  14)  are  30  inches  square,  and 
about  a  mile  of  these  have  been  built  running  up  the  bed  of  the 
stream,  besides  about  a  mile  of  perforated  pipe  30  inches  in 
diameter.  The  average  daily  yield  obtained  by  these  galleries 
is  nearly  10  acre-feet  of  water,  which  is  led  off  through  the  pipes 
by  natural  flow. 

1 20.  Other    Subsurface-water    Sources. — Earth    waters    may 
be  gathered  for  irrigation  by  other  means  than  springs,  common 
or  artesian  wells,  or  tunnels.     In  portions  of  the  plains  region, 
especially  in   Kansas,  subsurface  supplies  have  been  obtained 
by  running  long  and  deep  canals  parallel  to  the  dry  beds  of 
streams  or  in  the  low  bottom  lands  and  valleys.     These  canals, 
acting  like  drainage  ditches,  receive  a  considerable  supply  of 
water  and  lead  it  off  to  the  lands.     In  the  dry  beds  of  streams 
in  California  submerged  dams  have  been  built  which  reach  to 
some  impervious  stratum  and  cut  off  the  subterranean  flow,  thus 
bringing  the  water  to  the  surface.     In  some  experiments  made 
on  two  subcanals  in  Kansas  the  amount  of  water  obtained  was 
15  second-feet  for  each  mile  in  length  of  excavation,  which  was 
6  feet  in  depth  below  the  subsurface-water  plane.     (Art.  104.) 
It  was  found  that  the  depth  and  length  were  the  controlling  fac- 
tors, the  breadth  of  the  canal  having  little  effect  on  the  amount 
of  water  entering.     It  was  also  found  that  the  increase  of  flow 
due  to  the  deeper  cuts  was  nearly  equal  to  the  square  of  the  depth. 
It  may  be  generally  stated  that  the  amounts  of  water  to  be  derived 
by  such  means  are  very  limited  and  do  not  approach  those  claimed 
by  the  advocates  of  so-called  "  underflow." 

121.  Sewage    Disposal.— One   of    the    most    important    and 
difficult  problems  with  which  municipal  engineers  have  to  deal  is 
that  of  sewage  disposal.     In  the  humid  regions,  where  the  large 
cities  are  usually  found  close  to  rivers  of  some  magnitude  or  near 


108          SUBSURFACE-WATER     SOURCES    AND     SEWAGE 

the  ocean,  the  sewage  has  usually  been  easily  disposed  of  by  dis- 
charging it  into  the  natural  waterways  and  allowing  it  to  be 
carried  off  to  the  ocean.  In  the  arid  region  this  method  of  dis- 
posal is  not  so  easy  of  accomplishment,  because  of  the  lack  of 
waterways  into  which  to  discharge  it.  Difficulty  has  also  been 
encountered  in  some  of  the  older  inhabited  portions  of  the  world, 
and  as  a  result  other  and  newer  methods  of  disposing  of  sewage 
are  attracting  attention.  A  method  which  is  rapidly  gaining 
in  favor  is  by  flowing  the  sewage  over  the  soil  and  permitting  it 


FIG.  14. — Gathering-cribs,  Citizens'  Water  Co.,  Denver. 

to  filter  downward  through  this  and  find  its  way  to  the  natural 
watercourses.  It  has  been  found  that  nature  performs  the  chemi- 
cal and  mechanical  action  of  removing  the  heavy  matter  and 
purifying  the  more  liquid  portions  of  the  sewage  even  more  satis- 
factorily than  it  can  be  done  artificially.  This  has  naturally 
led  to  the  utilization  of  such  sewage  water  in  irrigating  crops,  and 
this  method  of  disposal  of  sewage  is  of  especial  interest  to  the 
people  of  the  arid  West. 

It  is  found  that  by  this  means  the  disposal  of  sewage  may 


SEWAGE   IRRIGATION  IOQ 

not  only  be  rendered  a  simple  matter,  but  that,  instead  of  being 
an  item  of  great  expense  to  the  municipality,  it  may  even  in  a 
few  instances  be  rendered  a  source  of  income.  The  use  of  sewage 
for  irrigation  has  been  practised  for  many  years  quite  extensively 
in  various  portions  of  Europe,  notably  at  Paris,  which  thus  dis- 
poses of  one-third  of  its  sewage;  at  Berlin,  which  uses  all  its 
sewage  for  irrigation;  at  Edinburgh,  Birmingham,  Florence, 
Milan,  Madrid,  and  many  other  cities  and  hundreds  of  smaller 
towns  which  maintain  sewage  farms.  In  our  own  country  this 
method  has  met  with  some  little  favor.  In  the  East  it  is  em- 
ployed successfully  at  Meriden,  Conn.,  and  Pullman,  111.,  and 
in  the  West  the  following  ten  cities  dispose  of  their  sewage 
by  irrigation:  Colorado  Springs,  Trinidad,  Fresno,  Pasadena, 
Redding,  Los  Angeles,  Santa  Rosa,  Helena,  Cheyenne,  and 
Stockton,  with  populations  varying  between  one  thousand  and 
fifty  thousand  inhabitants.  It  will  thus  be  seen  that  this  is  no 
new  problem  either  in  engineering  science  or  municipal  govern- 
ment. It  is  well  tried,  and  has  been  practised  for  a  couple  of 
centuries  in  some  European  countries,  and  in  every  case  where 
the  soil  is  suitable  has  been  found  an  economical  and  satisfactory 
method  of  disposing  of  sewage. 

122.  Sewage  Irrigation. — Sewage  may  be  disposed  of  by 
discharging  it  on  land  in  practically  three  ways,  namely,  by 
intermittent  downward  filtration,  by  broad  irrigation,  and  by 
a  combination  of  these  two  methods.  Intermittent  downward 
filtration  is  simply  a  mode  of  purifying  sewage,  by  applying  it 
to  land  without  making  any  attempt  to  utilize  it  in  irrigation, 
or,  in  other  words,  in  the  watering  and  cultivation  of  crops.  It 
requires  a  much  smaller  area  of  land  than  where  it  is  used  in 
irrigation.  It  depends  for  its  utility  on  the  fact  that  sewage 
passed  through  porous  soil  becomes  aerated  and  rapidly  purified 
through  the  oxidizing  action  of  the  air  which  the  soil  holds  in 
its  pores,  and  for  its  successful  operation  requires  that  the  sewage 
shall  not  be  passed  through  the  same  piece  of  land  continuously, 
but  at  long  enough  intervals  in  order  to  permit  the  soil  to  become 
aerated.  By  thus  intermittently  resting  the  soil  the  sewage  from 
500  to  1000  people  per  acre  can  be  purified.  This  system  in 


110  SUBSURFACE- WATER    SOURCES    AND     SEWAGE 

itself  is  of  little  interest  to  irrigators,  and  therefore  will  not  be  fur- 
ther described. 

The  utilization  of  sewage  by  broad  irrigation  requires  the 
employment  of  a  much  larger  tract  than  for  intermittent  down- 
ward filtration,  one  acre  of  land  being  sufficient  to  utilize  the 
sewage  of  from  150  to  500  people.  This  system  has  been  largely 
and  successfully  used,  especially  where  the  soil  is  porous  and 
underlain  by  a  deep  porous  subsoil.  When  the  farm  is  properly 
laid  out  and  carefully  managed  the  effluent  water  is  pure  enough 
to  be  practically  harmless  when  returned  to  the  natural  drainage 
channels.  One  of  the  most  serious  objections  to  the  disposal 
of  sewage  by  irrigation  is  the  fact  that  the  farmer  must  take  the 
sewage  at  all  times,  even  though  he  have  more  than  he  wants 
and  it  hurts  his  land.  It  has  been  found,  however,  that  a  com- 
bination of  the  above  methods,  in  which  intermittent  filtration  is 
used  as  a  supplement  to  broad  irrigation,  practically  overcomes 
this  disadvantage,  and  is  the  most  satisfactory  method  of  dis- 
posing of  and  utilizing  sewage  on  land.  This  is  done  by  laying 
out  a  small  portion  of  the  land  as  a  filter-bed  by  providing  it  with 
ample  underdrainage,  and  on  this  the  sewage  is  discharged  at 
such  times  as  it  is  not  needed  in  irrigation. 

123.  The  Fertilizing  Effects  of  Sewage. — It  is  well  known 
that  the  excrement  of  human  beings  is  far  richer  in  nitrogenous 
substances  than  that  of  any  other  animal,  and  that  it  has  a  far 
greater  fertilizing  value.  Human  excrement  loses  its  fertilizing 
value  rapidly  by  decomposition,  and  it  is  therefore  necessary  to 
apply  it  to  the  soil  within  a  few  days,  and  to  this  end  the  only 
practical  way  of  moving  it  is  by  water  carriage.  It  can  thus 
be  moved  as  much  as  fifty  miles  without  deteriorating,  while  the 
volume  of  carrying-water  need  never  exceed  10  cubic  feet  daily 
per  individual,  or  about  the  proportion  of  water  to  excreta  which 
usually  finds  its  way  into  city  sewage. 

On  the  sewage  farms  of  Paris  the  most  varied  products,  from 
vegetables  of  all  kinds  to  flowers  and  fruits,  are  profitably  grown. 
The  cultivation  of  vegetables  is  predominant,  cabbages  and 
cauliflower  being  especially  prolific.  The  sewage  water  is  em- 
ployed as  a  manure  or  for  watering  grain,  mangel-worzel,  and 


EFFECTS    OF    SEWAGE    IRRIGATION   ON   HEALTH        III 

meadows.  Lucerne  is  cut  as  often  as  four  or  five  times  a  season, 
and  mangel-wurzel  produces  as  much  as  40  tons  per  acre.  The 
municipal  engineers  of  Paris  state  that  the  rent  value  of  lands 
irrigated  by  sewage  has  increased  in  value  since  their  reclama- 
tion from  100  to  400  per  cent.  At  Colorado  Springs  enormous 
crops  are  reported  to  be  raised  from  sewage  irrigation,  while  the 
lessee  of  the  right  to  use  the  city  sewage  is  not  troubled  with  the 
vexatious  problem  of  priority  of  rights.  The  sewage  of  the  city 
of  Fresno,  Cal.,  is  used  in  irrigating  a  large  tract  of  land  on  which 
all  varieties  of  vegetables  are  profitably  grown.  The  best  evi- 
dence obtainable  indicates  that  the  fertilizing  effects  of  sewage 
are  not  as  great  as  claimed,  and  that  the  crops  raised  by  its  use 
in  humid  regions  are  scarcely  more  abundant  than  those  gotten 
by  use  of  chemical  fertilizers.  In  the  arid  regions  it  produces 
better  crops  than  water  alone,  but  scarcely  better  than  those 
gotten  by  the  use  of  water  with  artificial  fertilization.  Thorough 
cultivation  of  the  soil  greatly  increases  its  value  as  a  fertilizer. 

124.  Effects  of  Sewage  Irrigation  on  Health. — Fears  have 
been  entertained  that  sewage  farms  would  prove  dangerous  to 
the  health  of  the  neighboring  districts,  and  that  the  crops  grown 
on  them  would  be  unwholesome.  These  fears,  however,  have 
undoubtedly  proven  groundless,  as  shown  by  experience  in  many 
portions  of  the  world.  It  is  found  that  the  combined  action  of 
soil  and  vegetation  furnishes  the  true  solution  of  the  problem 
of  sewage  disposal  on  land.  It  satisfies  the  sanitary  conditions, 
and  at  the  same  time  gains  for  agriculture  a  source  of  manure 
and  water  which  would  otherwise  run  to  waste.  The  principle 
on  which  this  system  rests  is,  that  when  pure  water  charged  with 
materials  in  suspension  and  solution  is  flooded  over  permeable 
soil  the  upper  bed  of  this  acts  as  a  filter,  and  all  matter  in  sus- 
pension is  separated  by  mechanical  action.  After  this  superficial 
mechanical  filtration  the  water  reaches  the  roots  of  the  plants, 
which  absorb  with  benefit  the  fertilizing  substance  remaining 
in  solution.  Lastly,  as  the  waters  which  have  escaped  the  ab- 
sorbent action  of  the  plants  or  the  retentive  action  of  the  soil  con- 
tinue their  descent  through  a  subsoil  either  naturally  or  artificially 
permeable,  they  undergo  in  this  an  oxidizing  action  which  changes 


112  SUBSURFACE-WATER     SOURCES     AND     SEWAGE 

them  from  organic  substances  into  nitrates  or  nitrites — purely 
mineral  substances,  which  present  no  danger  of  fermentation, 
and  are  harmless  when  sufficiently  diluted. 

Chemical  analyses  of  the  waters  flowing  from  the  Paris  sewage 
farms  show  no  sensible  trace  of  decomposable  nitrogen  and  but 
little  more  than  a  trace  of  nitrogen  in  the  state  of  a  mineral  am- 
monia. On  the  other  hand,  where  no  vegetation  exists  on  the 
surface  a  very  perceptible  and  dangerous  quantity  of  nitrogen 
has  been  obtained.  It  was  also  discovered  that  the  descent 
through  the  porous  soil  insures  a  satisfactory  aeration,  as  sewage 
water  flowed  on  the  surface  and  containing  scarcely  any  oxygen 
issues  from  a  bed  of  stony  earth  but  six  feet  in  depth  with  a  gain 
of  from  400  to  600  per  cent  of  oxygen,  so  that  there  was  a  com- 
plete revivification  of  the  sewage  water,  which  was  not  merely 
clarified,  but  actually  purified.  Water  has  been  drawn  from 
wells  sunk  in  the  middle  of  lands  irrigated  by  sewage,  and  this 
water  has  been  found  to  be  perfectly  clear  and  identical  in  ap- 
pearance and  taste  with  waters  of  the  subterranean-water  plane 
which  supplies  wells  elsewhere  in  the  neighborhood  of  Paris. 
The  experience  at  the  Pullman,  111.,  farm  is  similar,  as  there  the 
superintendent  of  the  farm  lives  in  a  handsome  house  in  the  centre 
of  the  irrigated  area,  and  is  in  no  way  affected  or  annoyed  by 
the  sewage. 

Thorough  tilling  of  the  soil  after  each  flowing  of  sewage  is 
essential,  and  it  is  by  the  creation  of  a  proper  tilth  that  the  aera- 
tion of  the  sewage  and  incorporation  of  the  solid  matter  with  the 
soil  is  accomplished.  It  is  this  process  of  absorption  of  the  water, 
incorporation  of  the  deposits  with  the  soil,  and  its  utilization 
by  plants  that  guarantees  the  salubrity  of  the  surrounding  country. 
Villages  which  have  sprung  up  in  the  neighborhood  of  sewage 
farms  in  Europe  show  no  signs  of  disorders  or  diseases  of  any 
kind.  A  more  surprising  fact  is,  that  there  is  practically  no 
stench  from  the  flowing  of  sewage  over  the  land.  When  put  on 
the  land  with  no  more  dilution  than  the  flushing  water,  there  is 
at  that  time  a  perceptible  and  disagreeable  odor,  but  as  soon  as 
the  soil  has  been  cultivated  this  entirely  disappears. 

125.  Duty  of  Sewage. — Chemical  analysis  of  sewage  water 


DUTY    OF     SEWAGE  113 

indicates  that  the  theoretical  amount  which  may  be  used  in  irrigat- 
ing crops  with  benefit  to  agriculture,  and  which  the  soil  and 
crops  will  deprive  of  nitrogen,  alkalies,  and  phosphoric  acid, 
which  elements  most  affect  the  purity  of  water,  is  4.5  acre-feet 
per  acre.  However,  where  several  crops  are  produced  in  a  single 
season  on  the  same  soil,  and  more  especially  where  these  crops 
consist  of  alfalfa  and  similar  plants  which  require  heavy  watering 
by  flooding  methods,  as  much  as  12  to  15  acre-feet  per  acre  may 
be  applied  without  harmful  effect.  On  the  sewage  farms  of 
Gennevilliers,  in  the  suburbs  of  Paris,  the  average  annual  appli- 
cation of  sewage  during  ten  years  varied  between  15  and  22  acre- 
feet  per  acre.  This  soil,  it  seems,  is  especially  well  adapted  to 
the  purpose,  as  it  consists  of  a  bed  of  alluvium  from  20  to  30  feet 
in  depth,  and  composed  of  sand  and  gravel  interspersed  with  a 
little  vegetable  mould.  It  is  believed  that  this  natural  filter-bed 
will  remain  in  good  condition  even  after  the  formation  of  mud 
many  feet  in  depth.  It  has  been  found,  however,  that  the  average 
depth  of  deposit  for  10  years  does  not  exceed  0.5  of  an  inch.  It 
appears,  also,  that  these  deposits  are  not  foul  or  dirty,  as  they 
contain  as  much  as  50  per  cent  of  silicious  matter  which  renders 
them  friable  and  permeable,  and  the  cultivation  of  the  soil  each 
year  incorporates  this  deposit  with  the  soil,  resulting  in  the  main- 
tenance and  increase  of  the  arable  earth. 

At  the  Colorado  Springs  sewage  farm  the  sewage  of  12,000 
people  has  been  beneficially  disposed  of  in  irrigating  15  acres  of 
meadow  and  alfalfa  and  10  acres  of  vegetables.  This  is  approxi- 
mately at  the  rate  of  i  acre  to  500  inhabitants.  At  Pasadena, 
California,  the  sewage  of  6000  people  is  beneficially  used  in  irri- 
gating about  40  acres,  or  at  the  rate  of  about  i  acre  to  150  inhab- 
itants. At  Los  Angeles,  California,  the  entire  sewage,  which 
averages  105  second-feet  flowing  constantly,  has  been  used  in 
irrigating  1 700  acres ;  this  is  the  sewage  of  50,000  people,  so  that 
it  was  employed  at  the  rate  of  about  30  individuals  per  acre,  also 
about  at  the  rate  of  40  acre-feet  per  acre  per  annum.  At  Santa 
Rosa,  California,  20  acres  of  land  are  employed  in  disposing  of  the 
sewage  of  5200  people,  and  at  Helena,  Montana,  40  acres  in  dispos- 
ing of  the  sewage  of  14,000  people.  At  the  Meriden,  Connecticut, 

8 


114          SUBSURFACE-WATER    SOURCES    AND    SEWAGE 

broad  irrigation  and  intermittent  filtration  farm,  one  of  the  most 
modern  laid  out  in  this  country,  the  sewage  of  15,000  people, 
amounting  to  about  3  second-feet  running  continuously,  is  being 
successfully  treated  and  disposed  of  on  less  than  14  acres — a 
rate  of  150  acre-feet  per  acre. 

It  must  be  remembered,  however,  that  the  above  figures  do  not 
represent  the  ultimate  duty  of  sewage  as  such.  They  show  rather 
the  limits  in  amount  of  sewage  which  may  be  disposed  of,  that  is, 
the  extreme  amounts  which  may  be  utilized  on  a  given  area  with- 
out harmful  effects,  rather  than  the  minimum  amount  which  may 
be  utilized  with  beneficial  effects  to  the  crops.  In  other  words, 
they  show  the  limits  to  which  sewage  may  be  disposed  as  a  sani- 
tary problem,  rather  than  the  limit  of  crop  which  may  be  irrigated 
with  a  given  amount  of  sewage  as  an  irrigation  problem.  It  is 
not  unlikely  that  where  sewage  is  used  rather  for  its  value  as  an 
irrigating  material  than  otherwise  the  sewage  of  as  few  as  from 
50  to  100  people  may  suffice  to  irrigate  an  acre,  and  that  not 
over  4  to  6  acre-feet  in  depth  per  annum,  allowing  for  waste  in 
winter,  will  produce  satisfactory  and  beneficial  effects  in  irrigation. 

126.  Methods  of  Laying  out  Sewage  Farms  and  Applying 
Sewage. — In  preparing  land  for  sewage  irrigation  it  must  be 
remembered  that  the  sewage  cannot  be  disposed  of  continu- 
ously on  the  same  piece  of  land  with  benefit  to  crops,  but  that  it 
must  be  rotated  from  one  plot  to  another  so  as  to  give  each  a  rest 
and  permit  of  the  soil  being  cultivated  and  the  crops  handled. 
With  this  end  in  view  it  has  been  found  that  the  most  satisfactory 
way  of  laying  out  a  sewage  farm  is  to  divide  it  into  many  very  small 
tracts  or  plots  of  about  one  acre  in  extent  each,  so  arranged  and 
subdivided  by  distributing  channels  that  the  sewage  may  be 
applied  to  them  separately  and  independently.  Experience  has 
shown  that  first  of  all  the  soil  must  be  of  suitable  texture,  and  care 
should  be  taken  in  choosing  a  location  in  which  may  be  found  a 
deep  and  light  surface  soil,  underlain  if  possible  by  a  deep  and 
porous  subsoil,  preferably  of  sand  and  gravel.  If  the  slopes  of 
these  are  such  as  to  furnish  good  natural  drainage,  no  difficulty 
is  likely  to  arise  in  utilizing  such  land  for  an  indefinite  period  of 
time  under  proper  treatment. 


METHODS    OF    LAYING    OUT    SEWAGE    FARMS  115 

The  sewage  farm  at  Meriden,  Connecticut,  consists  of  three 
feet  of  fine  material  at  the  surface,  below  which  is  a  deep  layer 
of  sand  and  gravel  which  acts  admirably  as  a  filter-bed.  This 
land,  however,  was  at  first  very  much  overworked,  only  a  small 
area  being  utilized  in  disposing  of  the  sewage.  It  has  since  been 
successfully  revivified  and  put  in  condition  for  suitable  operation 
for  many  years,  by  thoroughly  cleaning  the  surface  and  scraping 
and  ploughing  to  a  depth  of  14  inches.  Moreover,  a  number  of 
ditches  3  feet  wide  were  sunk  down  into  the  subsoil,  the  finer 
material  being  removed  and  replaced  by  gravel.  In  this  way  the 
surface  was  connected  with  the  gravel  or  natural  filter-bed  by  the 
simplest  form  of  artificial  drainage.  In  cleaning  the  filter-bed 
it  was  found  that  the  sludge  which  had  dried  hard  by  exposure  to 
the  atmosphere  could  be  raked  off  into  piles  and  carted  away. 
It  was  also  found  that  over  the  greater  part  of  the  area  the  depth 
of  this  was  scarcely  one-eighth  of  an  inch  after  three  years  of 
usage,  though  this  increased  to  nearly  6  inches  at  the  outlet  of  the 
sewage  drain.  In  making  additional  sewage  plots  at  the  same 
farm  a  depth  of  about  two  feet  of  the  close-grained  surface  soil 
has  been  removed  and  the  remainder  ploughed  to  a  depth  of  about 
14  inches,  reaching  a  few  inches  into  the  gravel  beneath.  The 
cost  of  preparation  of  this  farm  has  been  nearly  as  great  as  one 
thousand  dollars  per  acre,  but  this  is  owing  largely  to  the  very 
small  area  employed  and  the  inferior  quality  of  surface  soil.  At 
the  Paris  sewage  farms  the  water  is  brought  from  the  city  in 
closed  sewers  and  then  in  an  open  drain,  and  finally  is  distributed 
through  the  55  acres  of  irrigated  fields  in  about  3.5  miles  of  open 
surface  channels. 

After  a  suitable  soil  has  been  chosen  and  the  land  has  been 
underdrained  or  otherwise  suitably  prepared,  it  should  be  divided 
by  open  drains,  preferably  lined,  into  plots  of  from  200  to  400  feet 
on  a  side.  The  sewage  should  be  brought  to  the  limits  of  the  farm 
in  closed  sewer  conduits,  which  must  be  properly  ventilated.  It 
is  desirable  at  the  outlet  of  the  conduit  at  the  entrance  of  the 
farm  to  construct  a  small  storage  reservoir,  suitably  lined,  since 
it  may  be  necessary  to  retain  the  sewage  of  at  least  twenty -four 
hours,  and  certainly  of  a  night,  at  times  when  it  is  not  possible 


Il6          SUBSURFACE-WATER    SOURCES    AND    SEWAGE 

to  use  it.  A  screen  should  be  placed  at  the  head  of  the  farm  dis- 
tributaries in  order  to  keep  out  such  matter  as  it  is  not  desirable 
to  use  in  irrigation,  and  this  may  be  removed  at  certain  intervals, 
either  to  waste  land,  where  it  may  be  ploughed  under,  or  may  be 
disposed  of  by  cremation  or  other  process.  The  most  satisfactory 
mode  of  constructing  such  a  reservoir  so  that  no  odor  shall  emanate 
from  it  is  to  cover  it  with  a  rough  board  roof  and  build  a  ventilat- 
ing chimney,  which  can  be  constructed  cheaply  of  lumber  and 
should  not  be  less  than  50  feet  in  height.  Such  a  chimney  is 
sufficient  to  prevent  any  nuisance,  either  from  the  reservoir  or 
from  sewage  flowed  therefrom  on  to  the  fields.  By  such  means 
sewage  which  is  used  on  freshly  irrigated  land  scarcely  emits 
the  slightest  odor,  while  none  is  perceptible  immediately  after 
ploughing. 

The  most  satisfactory  way  of  applying  sewage  for  irrigation 
is  through  furrows  between  rows  of  vegetables,  the  simple  furrow 
method  of  irrigation  (Chap.  XIV)  being  employed.  In  some 
cases,  however, — notably  at  Trinidad,  Colorado, — the  em- 
bankment or  check  method  has  been  employed,  more  especially 
in  the  cultivation  of  grain  and  forage  crops.  After  applying 
sewage  to  crops  it  is  left  only  so  long  as  to  permit  it  to  become 
dry  enough  to  work,  when  the  land  is  thoroughly  tilled  and  all 
solid  matter  turned  over  before  the  next  application  of  sewage, 
while  such  a  variety  of  crops  must  be  employed  as  to  make  the 
irrigation  season  as  long  as  possible.  During  the  non-irrigating 
period,  the  winter  months,  the  sewage  may  be  flowed  in  rotation 
over  various  plots  of  land  and  be  permitted  to  filtrate  through  this 
and  find  its  way  back  to  the  natural  drainage  channels.  It  is  desir- 
able, however,  to  use  precaution  and  not  overcharge  the  land,  and 
this  may  be  prevented,  by  tilling  it  a  few  times  during  the  more 
open  days  of  winter.  As  soon  as  the  crops  are  to  be  sown  in 
spring  it  is  desirable,  should  too  great  an  accumulation  of  solid 
matter  appear  on  the  surface,  to  rake  this  off  before  planting 
the  season's  crops.  Experience  has  proven  that  sewage  reaches 
the  lands  at  a  sufficiently  high  temperature,  even  in  the  coldest 
weather,  to  permit  it  to  remain  unfrozen  and  to  find  its  way  by 
nitration  into  the  soil. 


WORKS    OF    REFERENCE  117 

127.  Works   of    Reference.     Subsurface- water    Sources    and 
Sewage  for  Irrigation. 

ALLEN,  CHARLES  A.,  and  Others.  Sewage  Disposal.  Trans.  Am.  Soc.  C.  E., 
Vol.  XVIII.  New  York,  1888. 

BUTLER,  W.  P.     Irrigation  Manual.     W.  P.  Butler,  Aberdeen,  S.  D.,  1892. 

CHAMBERLAIN,  T.  C.  The  Requisite  and  Qualifying  Conditions  of  Artesian 
Wells.  Fifth  Annual  Report,  U.  S.  Geological  Survey.  Washington,  D.  C., 
1884. 

DARTON,  N.  H.  Preliminary  List  of  Deep  Borings.  U.  S.  Geological  Survey, 
Water  Supply  Paper  No.  61.  Washington,  D.  C.,  1902. 

ENGINEERING  NEWS.  "Sewage  Purification  in  America."  New  York,  Feb- 
ruary 23,  1893;  July  1 8,  1894. 

HALL,  WM.  HAM.  Irrigation  in  Southern  California.  Part  II,  Annual  Report  of 
State  Engineer.  Sacramento,  1888. 

HAMLIN,  HOMER.  Underflow  Tests.  Water  Supply  Paper  No.  112,  U.  S.  Geo- 
logical Survey.  Washington,  D.  C.,  1905. 

HAY,  PROF.  ROBT.,  and  Others.  Geological  Reports  on  Artesian  Underflow  In- 
vestigations. Department  of  Agriculture,  Washington,  D.  C.,  1892. 

HILL,  PROF.  ROBT.  T.,  and  Others.     Same  as  preceding. 

JACKSON,  Louis  D'A.     Hydraulic  Works.     W.  Thacker  &  Co.,  London,  1885. 

MANNING,  ROBERT.     Sanitary  Works  Abroad.     E.  &  F.  N.  Spon,  London,  1876. 

NETTLETON,  E.  S.  Artesian  and  Underflow  Investigations.  Department  of 
Agriculture,  Washington,  D.  C.,  1892. 

NEWELL,  F.  H.  Artesian  Wells  for  Irrigation.  U.  S.  Census  Bulletin  No.  193. 
Washington,  D.  C.,  1890. 

NEWELL,  F.  H.  Agriculture  by  Irrigation.  Report  at  Eleventh  Census,  1890. 
Washington,  D.  C.,  1894. 

—  Drilling  and  Care  of  Oil-wells.     Report  Geological  Survey  of  Ohio,  Volume 
6.     Columbus,  1888. 

ORME,  S.  H.     Sewage  Irrigation.     Engineering  News.     New  York,  July  5,  1894. 

POWELL,  J.  W.  Artesian  Wells.  Part  II,  Eleventh  Annual  Report,  U.  S.  Geo- 
logical Survey.  Washington,  D.  C.,  1890. 

RAFTER,  GEO.  W.,  and  BAKER,  M.  N.  Sewage  Disposal  in  the  United  States. 
D.  Van  Nostrand  Co.,  New  York,  1894. 

REID,  H.  I.  Utilization  of  Sewage  for  Irrigation  Purposes.  Annual  of  American 
Society  of  Irrigation  Engineers.  Denver,  Colorado,  1893. 

SLIGHTER,  C.  S.  The  Rate  of  Movement  of  Underground  Waters.  U.  S.  Geo- 
logical Survey,  Water  Supply  Paper  No.  140.  Washington,  D.  C.,  1905. 

SPON,  ERNEST.  Present  Practice  of  Sinking  and  Boring  Wells.  E.  &  F.  N. 
Spon,  London,  1885. 

WALL,  NORVEL  W.  Disposal  of  Sewage  of  Trinidad,  Colorado,  by  Irrigation. 
Annual  of  American  Society  of  Irrigation  Engineers.  Denver,  Colorado,  1893. 


Part    Two 
CANALS  AND  CANAL  WORKS 


CHAPTER  VIII 

CLASSES    OF   IRRIGATION    WORKS 

128.  Gravity  and  Lift  Irrigation. — Irrigation  works  may 
be  divided  into  the  above  two  great  classes.  Gravity  works 
include  all  those  by  which  the  water  is  conducted  to  the  land  with 
the  aid  of  gravity  or  natural  flow.  They  include — 

1.  Perennial  canals;- 

2.  Periodical  and  intermittent  canals; - 

3.  Inundation  canals;- 

4.  Storage  works; 

5.  Artesian-water  supplies; - 

6.  Subsurface-  or  ground-water  supplies.  - 

Lift  irrigation  includes  those  forms  of  irrigation  in  which  the 
water  does  not  reach  the  land  by  natural  flow,  but  is  transported 
to  it  by  pumping  or  other  means  of  lifting.  It  may  be  divided  into 
two  main  classes: 

1.  Irrigation  by  watering-pots,  hose,  or  sprinkling-carts; 

2.  Irrigation  by  pumping. 

The  first  needs  no  explanation;  the  last  may  be  divided  into 
four  principal  classes : 

1.  Pumping  by  animal  power; 

2.  Pumping  by  water-power; 

3.  Pumping  by  windmills; 

4.  Pumping  by  mechanical  power. 

The  sources  of  supply  for  all  forms  of  gravity  irrigation  are 
defined  by  the  titles  of  the  classes.  They  are  from  perennial 
streams,  intermittent  streams,  artesian  wells,  submerged  dams, 

118 


NAVIGATION    AND     IRRIGATION     CANALS  IIQ 

tunnels  or  cuts,  or  by  the  storage  of  perennial,  intermittent,  or 
flood  waters.  The  sources  of  supply  for  lift  irrigation  may  be 
from  wells,  canals,  storage  works,  lakes,  or  streams. 

129.  Navigation    and    Irrigation    Canals. — Canals    may    be 
used  for  irrigation  alone  or  for  irrigation  and  navigation  com- 
bined.    The  conditions  required  to  develop  an  irrigation  canal 
are:  first,  that  it  shall  be  carried  at  as  high  a  level  as  possible  so 
as  to  have  sufficient  fall  to  irrigate  the  land  to  a  considerable  dis- 
tance on  both  sides;    second,  it  should  be  fed  by  some  source 
of  supply  that  will  render  it  a  running  stream,  so  that  the  water 
used  in  irrigation  may  be  constantly  replaced;    third,  it  should 
have  such  a  slope  and  velocity  as  to  reduce  to  a  minimum  the 
deposition  of  sediment  and  the  growth  of  weeds;  fourth,  its  velo- 
city should  be  the  greatest  possible  in  order  that  the  cross-section 
may  be  reduced  to  a  minimum  for  a  given  discharge.     Naviga- 
tion, on  the  other  hand,  requires  of  a  canal :   first,  that  the  water 
in  it  shall  be  as  nearly  still  as  possible,  so  that  navigation  may 
be  equally  easy  in  both  directions;    and,  second,  it  requires  no 
further  supply  of  water  than  is  necessary  to  replace  the  loss  by 
evaporation  and  absorption,  and  at  the  points  of  transfer  from 
higher  to  lower   levels.     It  is  thus  seen  that  the   requirements 
of  the  two  classes  are  conflicting,  and  it  is  not  deemed  good 
practice  to  make    irrigation    canals    available   for    purposes  of 
navigation. 

130.  Sources  of  Supply. — The  climate,  geology,  and  topog- 
raphy are  the  chief  factors  in  deciding  the  class  of  work  which 
belongs  to  a  given  region.     Where  the  precipitation  is  small, 
occurring  during  a  short  period  of  the  year,  and  resulting  in  the 
intermittent  or  periodical  flow  of  the  streams,  canals  of  this  class 
or  storage  works  must  be  employed.     Intermittent  and  periodical 
canals  are  usually  very  small  in  dimensions,  commanding  rela- 
tively small  areas  of  land,  and  are  generally  employed  by  in- 
dividual farmers  for  the  utilization  of  the  waters  of  some  stream 
which  may  be  safely  counted  upon  for  a  temporary  supply  during 
a  few  occasional  spring  storms  or  the  melting  of  the  mountain 
snows.     They  can  only  be  used  with  safety  where  the  precipitation 
is  nearly  sufficient  for  the  cultivation  of  crops  and  the  little  water 


120  CLASSES    OF    IRRIGATION    WORKS 

which  they  supply  is  of  value  in  helping  this  out.  Storage  works 
receive  their  supply  from  intermittent  streams  carrying  sufficient 
volumes  of  water  at  flood  times,  or  perhaps  from  perennial  streams 
artesian  wells,  or  in  fact  from  any  source  from  which  a  permanent 
supply  of  water  may  be  obtained.  Inundation  canals  are  used 
almost  exclusively  in  India  and  Egypt,  and  derive  their  supply 
from  streams  the  beds  of  which  are  at  an  altitude  relatively  high 
compared  with  the  surrounding  country.  They  are  thus  supplied 
by  flood  waters  which  flow  above  the  general  level  of  the  sur- 
rounding country,  and  rarely  require  any  permanent  headwork 
to  control  the  entrance  of  the  water  into  the  canal. 

Artesian  wells  derive  their  supply  from  artesian  water  sources, 
which  have  their  origin  usually  at  some  great  distance  and  at  an 
altitude  considerably  higher  than  the  outlet  of  the  well.  Sub- 
surface cuts,  tunnels,  and  wells  derive  their  supplies  from  the 
seepage  water  with  which  the  soil  in  nearly  every  country  is  per- 
meated (Chap.  VI). 

131.  Inundation  Canals. — Inundation  canals  might  also  be 
called  flood-height  canals,  as  they  are  dependent  for  their  water- 
supply  on  the  height  of  flood  rise  in  the  river  from  which  they  are 
diverted.  This  variety  of  canals  is  employed  most  satisfactorily 
in  connection  with  rivers  which  have  built  up  their  beds  by  the 
deposition  of  sediment,  and  therefore  practically  flow  on  the 
summits  of  ridges.  The  most  notable  of  these  are  the  Indus  in 
India  and  the  Nile  in  Egypt.  There  are  a  number  of  such  streams 
in  this  country,  as  the  Sacramento  and  the  lower  portions  of  the 
Yuba  and  Feather  rivers  in  California,  the  beds  of  which  are  in 
some  places  at  considerable  heights  above  the  surrounding  country. 
The  lower  Mississippi  belongs  to  the  same  class  of  streams. 

Inundation  canals  rarely  require  any  permanent  headworks 
for  the  control  and  admission  of  water  to  their  channels,  their 
heads  consisting  of  a  simple  cut  through  the  river  bank  or  ridge 
which  separates  the  river  from  the  low-lying,  surrounding  country. 
As  they  depend  upon  flood  rises  for  their  supply,  the  beds  of  these 
canals  are  generally  at  some  height  above  the  beds  of  the  rivers 
from  which  they  are  diverted,  and  usually  at  the  level  of  mean  or 
low  water,  so  that  when  these  streams  are  not  in  flood  they  do 


INUNDATION    CANALS  121 

not  receive  any  supply  and  are  therefore  not  perennial  canals. 
Heads  on  such  canals  are  usually  situated  in  the  true  bank  of  the 
main  river  from  which  they  draw  their  supply,  but  at  such  a 
position  that  they  are  not  in  a  cutting  bank  or  one  against  which 
in  its  meanderings  the  river  impinges,  lets  it  destroy  the  bank  at 
this  point,  and  thus  the  headwork,  as  occurred  on  the  Colorado 
river  below  Yuma  when  it  filled  Salton  sea  in  1905.  It  is  not  un- 
common, however,  to  locate  the  headworks  in  sloughs  or  bayous 
which  are  found  adjacent  to  rivers  of  this  character.  Such 
sloughs  are  generally  larger  than  the  canals  which  they  thus  feed, 
and  the  velocity  of  the  water  being  less  in  them,  as  a  consequence 
the  silt  which  might  otherwise  be  deposited  in  the  canals  is  left 
in  the  sloughs. 

There  are  many  such  inundation  canals  taken  from  the  river 
Indus.  The  difference  in  elevation  between  ordinary  water  stage 
and  inundation  level  of  this  river  is  from  8  to  12  feet.  The 
velocity  of  the  river  is  in  some  places  greater  than  the  nature  of 
the  banks  will  stand,  and  therefore  the  heads  of  the  inundation 
canals  have  to  be  opened  afresh  every  year.  These  canals  vary 
in  bed-width  from  6  to  50  feet,  and  are  from  10  to  60  miles  in 
length.  They  carry  depths  of  water  during  flood  periods  of  from 
5  to  10  feet,  and  their  slopes  range  from  i  in  4000  to  i  in  10,000. 

The  inundation  canals  taken  from  the  Nile  in  Egypt  have 
usually  a  much  lighter  slope,  ranging  from  i  in  20,000  to  i  in 
33,000,  and  some  of  the  more  modern  of  these  have  permanent 
control  works  at  their  heads  with  regulating  bridges  and  escapes 
at  places  where  they  are  not  subject  to  destruction  by  floods. 
The  flood  rise  of  the  Nile  is  about  15  feet,  and  the  period  of  flood, 
which  commences  gradually  and  subsides  slowly,  is  from  August 
to  October,  and  after  its  subsidence  crops  are  sown  in  November 
and  reaped  in  spring.  The  water  of  the  Nile  is  not  always  de- 
livered to  the  ground  as  in  ordinary  irrigation  during  the  growing 
of  crops,  but  as  it  must  be  gotten  when  the  flood  is  at  its  height, 
and  this  is  the  case  with  most  inundation  canals,  it  is  permitted 
during  the  period  from  August  to  October  to  rest  in  basins  formed 
by  levees  or  embankments  separating  one  basin  from  another. 
By  standing  in  these  basins  it  deposits  its  silt  and  enriches  the 


122  CLASSES    OF    IRRIGATION    WORKS 

soil  and  at  the  same  time  soaks  the  ground  so  thoroughly  that 
after  the  subsidence  the  soil  retains  sufficient  moisture  to  mature 
crops.  In  the  older  methods  of  irrigation  from  the  Nile  the  water 
was  supplied  directly  from  the  river  into  the  upper  basin,  and 
flowed  from  this  through  to  the  lower  basins  and  then  back  to 
the  river.  Latterly,  however,  some  great  canals  have  been  built 
which  skirt  the  bluffs  of  the  river,  and  instead  of  pouring  the 
water  into  the  upper  basin  and  letting  it  run  from  one  basin  to 
another  until  it  reaches  the  lower  and  is  finally  discharged  from 
this  back  into  the  river,  it  is  admitted  to  many  basins  separately 
from  the  canal,  thus  furnishing  fresher  water  more  evenly  charged 
with  sediment  than  the  basins  would  have  received  by  the  old 
method. 

The  greatest  of  the  Egyptian  inundation  canals  is  the  new 
Ibrahimiyah  canal,  which  is  diverted  from  the  Nile  near  Assiout 
(Art.  354),  and,  skirting  the  western  edge  of  the  valley,  irrigates 
about  twenty  great  basins  and  a  number  of  smaller  ones,  contain- 
ing in  all  an  area  of  about  600,000  acres,  and  in  addition  500,000 
acres  of  high-level  and  Fayoum  crops  not  divided  into  "basins, 
making  a  total  of  1,100,000  acres  irrigated  by  it.  This,  though 
really  an  inundation  canal,  acts  practically  as  a  perennial  canal 
for  a  time,  as  its  bed  is  about  6  to  8  feet  below  ordinary  low  Nile, 
when  it  has  a  minimum  discharge  of  about  1500  second-feet. 
This  great  canal  is  about  160  miles  in  length,  has  a  bottom  width 
in  its  upper  reaches  varying  between  160  and  230  feet,  and  a 
maximum  depth  of  33  feet  with  a  surface  slope  of  i  in  22,000. 
Its  maximum  discharge  has  been  as  great  as  32,000  second-feet, 
and  it  is  quite  open  to  the  river  without  any  headworks  for  the 
control  of  the  water  entering  it.  The  first  regulating  work  on 
its  line  is  at  Derout,  where  the  water  can  be  drawn  from  the 
canal  by  great  regulating  works  into  five  branches  or  passed  into 
the  river  through  a  large  escape.  At  the  terminus  of  this  canal, 
at  the  lower  end  of  the  basin  system  near  Queshesha,  is  the  largest 
masonry  escape  in  the  world  for  discharging  the  water  which 
comes  from  the  canal  and  basins.  Its  maximum  capacity  is 
80,000  second-feet,  and  it  consists  of  60  vents  of  10  feet  each, 
the  maximum  height  on  it  being  calculated  at  nearly  15  feet.  It 


PERENNIAL    CANALS  123 

is  closed  by  a  series  of  great  double  gates  operated  by  travelling 
cranes  from  the  piers  above. 

132.  Perennial  Canals. — Perennial  canals  derive  their  supplies 
from  perennial  streams  or  from  storage  .reservoirs.     They  may 
be  divided  into  two  classes,  according  to  the  location  of  their  head- 
works.     These  are : 

1.  High-line  canals,  and 

2.  Low-service  or  deltaic  canals. 

High-line  canals  are  usually  of  moderate  size,  and  are  designed 
to  irrigate  lands  of  limited  area  which  lie  close  under  the  foot  of 
the  higher  hills.  They  are  generally  given  the  least  possible  slope, 
in  order  that  their  grades  may  remain  high  and  command  the 
greatest  amount  of  land.  In  such  canals  it  is  necessary  to  locate 
the  head  works  high  up  on  the  stream,  frequently  in  rocky  canyons 
where  the  first  portions  of  the  line  may  encounter  heavy  and 
expensive  rock-work.  Low-service  canals  are  constructed  where 
the  majority  of  the  lands  are  situated  in  low-lying  and  extensive 
valleys  and  where  the  location  of  the  head  of  the  canal  depends 
not  so  much  on  its  being  at  a  relatively  high  altitude  and  com- 
manding a  great  area  as  upon  the  suitability  of  the  site  for  pur- 
poses of  diversion.  High-line  canals  are  more  frequently  con- 
structed where  the  water-supply  is  abundant  and  it  is  desirable  to 
obtain  the  largest  amount  of  land  to  which  to  apply  it.  Low- 
service  canals  are  constructed  where  the  irrigable  lands  exceed 
in  area  the  amount  of  water  available. 

Deltaic  canals  have  been  constructed  chiefly  in  Egypt  and 
India  at  the  deltas  of  some  of  the  great  rivers,  as  the  Nile,  Ganges, 
Orissa,  and  others.  They  are  essentially  low-service  canals 
and  are  built  in  regions  where  the  slope  is  very  small.  As  a  con- 
sequence their  cross-sections  must  be  relatively  large,  that  they 
may  carry  a  given  discharge  with  the  least  velocity.  They  are 
tisually  navigable,  and  in  most  cases  their  water-supply  is 
abundant. 

133.  Dimensions  and   Cost  of   Some   Perennial  Canals. — In 
Table  XVII,  are  given  the  dimensions,  including  the  capacity 
and  area  commanded,  and  the  cost  in  various  terms,  of  some  of 
the  great  perennial  canals  of  the  world. 


124 


CLASSES    OF    IRRIGATION    WORKS 


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PARTS  OF  A  CANAL  SYSTEM  125 

134.  Parts  of  a  Canal  System. — The  machinery  of  a  great 
perennial  canal  consists  essentially  of  the  following  parts,  which 
are  treated  here  in  the  order  given: 

1.  Source  of  supply ; 

2.  Irrigable  lands; 

3.  Main  canal; 

4.  Head  and  regulating  works; 

5.  Control  and  drainage  works; 

6.  Distributaries  and  laterals. 

The  principal  units  of  this  system  are  the  main  canals  and  dis- 
tributaries. Between  different  canal  systems  the  greatest  points 
of  difference  are  found  in  the  headworks,  and  in  the  first  few 
miles  of  diversion  line,  where  numerous  difficulties  are  frequently 
encountered,  calling  for  variations  in  the  form  and  construction 
of  drainage  works  and  canal  banks. 

The  headworks  consist  usually  of  the  diversion  weir  with  its 
scouring  sluices,  of  the  head  regulating  gates  at  the  canal  en- 
trance, and  of  the  head  escape  or  sand  gates.  The  control  works 
consist  of  regulating  gates  at  the  head  of  the  branch  canals,  and 
of  escapes  on  the  line  of  the  main  and  branch  canals.  The  drain- 
age works  consist  of  inlet  or  drainage  dams,  flumes  or  aqueducts, 
superpassages,  inverted  siphons,  and  drainage  cuts.  In  addition 
to  these  works  there  are  usually  constructed  falls  and  rapids  for 
neutralizing  the  slope  of  the  country,  and  tunnels,  cuttings,  and 
embankments.  Modules  or  some  form  of  measuring  box  or 
weir  are  necessary  for  the  measurement  of  the  discharge. 


CHAPTER  IX 

ALIGNMENT,    SLOPE,    AND    CROSS-SECTION 

135.  Relation    between    Lands    and    Water-supply. — In    de- 
signing an  irrigation  work  the  first  consideration  is  the  land  to  be 
irrigated.     The  projector   must   consider  the   area  of   this,    its 
nearness  to  market,  the  quality  of  the  soil,  the  climate,  and  the 
character  and  value  of  the  crops  which  it  will  produce.     In  addi- 
tion the  value  and  ownership  of  the  land  must  necessarily  be  con- 
sidered.    All  of  these  quantities  having  been  satisfactorily  deter- 
mined and  the  necessity  of  supplying  water  for  irrigation  having 
been  ascertained,  the  next  question  is  the  source  of  supply  and  its 
relative  location  to  the  lands.     This  supply  may  be  found  in 
some  adjacent  perennial  stream,  or  it  may  be  necessary  to  trans- 
port it  across  an  intervening  ridge  from  a  neighboring  watershed, 
or  it  may  be  necessary  to  conserve  in  storage  reservoirs  the  flood 
flow  of  intermittent  streams.     The  relation  of  the  water-supply  to 
the  land,  the  extent  of  the  latter,  and  the  volume  and  permanency 
of  the  former  are  the  most  important  items  to  be  ascertained  in 
the  preliminary  investigation  of  any  irrigation  project. 

136.  Diversion   Works. — The    diversion    works    of    a    canal 
include  i,  the  works  for  directing  the  water  of  the  stream  into  the 
canal  entrance,  which  may  be  by  weir  or  by  training  works ;  2,  the 
mode  of  controlling  the  amount  of  water  admitted  to  the  canals, 
which  may  be  by  regulating  gates  at  its  head  or  by  simply  making 
an  open  cut  unregulated  as  in  inundation  canals;    3,  scouring 
sluices,  to  prevent  the  deposition  of  silt  at  the  canal  head;    4, 
escapes  or  sand  gates  in  the  upper  reaches  of  the  canal  line  for  the 
disposal  of  surplus  water  and  the  removal  of  sediment;    and  5, 
the  diversion  line  of  the  canal  itself,  or  that  portion  required  to 
bring  the  water  to  the  irrigable  land. 

The  first  problem  in  the  preliminary  design  of  a  canal  is  the 

126 


ALIGNMENT  127 

choice  of  the  point  of  diversion  or  site  for  the  headworks.  These 
are  usually  located  high  up  on  the  supplying  stream  in  order  to 
command  the  largest  area  possible  and  to  receive  water  from  the 
stream  before  the  latter  has  become  charged  with  silt  from  cutting 
its  banks  in  the  more  low-lying  country.  Occasionally,  however, 
where  the  area  of  land  to  be  commanded  is  limited,  it  may  be 
desirable  to  locate  the  headworks  at  some  lower  point  on  the 
stream.  By  locating  the  headworks  high  up  on  the  supply  stream 
it  is  usually  possible  to  reach  the  watershed  or  interfluve  by  the 
shortest  possible  diversion  line.  The  chief  disadvantage  of  such 
a  location  is  that  the  first  few  miles  of  diversion  line  are  sure  to  be 
intersected  by  sidehill  drainage,  the  passage  of  which  may  entail 
great  difficulty  and,  if  the  slopes  of  the  adjacent  country  are 
heavy,  much  expensive  hillside  cutting. 

By  " diversion  line"  is  meant  that  portion  of  the  canal  line 
which  is  required  in  order  to  bring  it  to  the  neighborhood  of  the 
irrigable  land.  The  endeavor  should  always  be  so  to  locate  the 
diversion  canal  as  to  reduce  its  length  to  a  minimum,  so  that  the 
canal  shall  command  irrigable  land  and  thus  derive  revenue  at 
the  earliest  possible  point. 

137.  Alignment. — Having  determined  the  source  of  water- 
supply,  and  its  relation  to  the  irrigable  lands,  the  next  question 
is  the  alignment  of  the  canal.  This  should  be  such  that  it  shall 
reach  the  highest  part  of  the  irrigable  lands  with  the  least  length 
of  line  and  at  a  minimum  expense  for  construction.  The  line  of 
the  canal  should  follow  the  highest  line  of  the  irrigable  land, 
preferably  skirting  the  surrounding  foothills  and  passing  down 
the  summits  of  the  watersheds  dividing  the  various  streams  in 
order  that  it  may  command  land  on  each  side  by  its  branches. 

Careful  preliminary  and  location  surveys  are  necessary  to 
procure  the  best  alignment.  That  all  possible  locations  may  be 
examined,  it  is  desirable,  first,  to  construct  a  general  topographic 
map  on  some  large  scale, — perhaps  800  to  1500  feet  to  the  inch,— 
and  with  contour  lines  showing  differences  of  elevation  of  from 
5  to  10  feet.  On  such  a  map  it  i3  possible  at  once  to  lay  down 
with  a  near  degree  of  approximation  the  final  position  of  the 
canal  line.  It  is  dso  frequently  possible  from  inspection  of  such 


128  ALIGNMENT,    SLOPE,    AND    CROSS-SECTION 

a  map  to  save  many  miles  of  canal  by  the  discovery  of  some  low 
divide  or  some  place  in  which  a  short  but  deep  cut  or  a  tunnel 
will  save  a  long  detour.  Having  laid  down  this  line  on  the  map, 
the  final  location  may  be  made  on  the  ground,  with  the  aid  perhaps 
of  a  few  short  trial  lines  to  determine  its  exact  position. 

138.  Method  of  Survey. — The  surveys  necessary  for  properly 
designing  and  building  a  canal  may  be  distinguished  as  hydro- 
graphic,  preliminary,  location,  and  construction  surveys.     The 
first  has  already  been  described  in  Chapters  II  to  V  inclusive,  and 
includes  all  problems  connected  with  the  quantity,  character,  and 
chemical  properties  of  the  water-supply.     The  construction  survey 
will  not  be  described  here  other  than  to  state  that  it  is  similar 
to  such  surveys  on  railway  or  other  engineering  work,  and  includes 
careful  cross-sectioning  of  the  canal  line ;  borings  and  trial  pits  to 
determine  the  nature  of  the  subsurface  formations ;    the  making 
of  detailed  estimates  of  the  volume  and  kind  of  material  to  be 
moved;   and  the  staking  out  of  the  line  on  the  ground  in  accoid- 
ance  with  these  estimates,  in  order  that  the  contractors  or  laborers 
may  know  just  where  and  how  to  work. 

Circumstances  will  determine  whether  both  a  preliminary  and 
a  location  survey  shall  be  made,  or  whether  once  going  over  the 
ground  will  suffice.  These  surveys  may  be  divided  into  two 
general  classes:  (i)  linear  or  trial-line  surveys,  and  (2)  contour 
topographic  surveys.  Where  a  contour  topographic  map  is  made, 
this  will  usually  answer  all  the  purposes  of  both  classes  of  survey. 
It  must  be  made  to  cover  such  an  area  of  ground  as  will  include 
all  possible  diversion  lines  as  well  as  main  lines,  branches,  and 
distributaries.  Such  a  survey  and  map  once  made,  it  is  the  pre- 
liminary survey,  and  on  it  the  location  may  be  laid  down  with 
accuracy  and  practical  finality,  and  it  will  in  all  liklihood  be 
necessary  to  deviate  from  such  a  location  but  little  as  construction 
progresses. 

139.  Linear  or  Trial-line  Survey. — Starting  from  the  upper  end 
of  the  irrigable  area,  run  a  level  line  back  up-stream  on  the  grade 
chosen  until  it  reaches  the  stream-bed.     Should  it  strike  this  at  a 
point  unfavorable  for  the  construction  of  headworks,  a  second 
trial  line  may  be  started  at  some  suitable  point  above  or  below 


LINEAR     OR     TRIAL-LINE     SURVEY  I2Q 

the  first  and  run  in  the  opposite  direction  with  the  same  grade,  or, 
if  it  has  been  started  up-stream,  with  the  insertion  of  a  fall  or 
two;  and  this  operation  may  be  repeated  until  such  a  line  is 
obtained  as  will  begin  at  the  most  desirable  site  for  headworks 
and  reach  the  irrigable  tract  at  the  highest  practical  elevation 
with  the  shortest  line  and  at  the  same  time  encounter  fewest 
obstacles. 

The  first  trial  line  or  two  run  as  above  serve  practically  as 
preliminary  lines.  They  should  therefore  be  run  with  long  sights, 
there  being  no  necessity  for  great  accuracy  in  levelling.  Only  a 
level  line  is  necessary,  the  chief  object  being  to  ascertain  the 
relative  elevations  of  the  proposed  sources  of  water-supply  and  the 
irrigable  lands. 

The  final  location  line  having  thus  been  approximately  deter- 
mined, it  should  be  fixed  by  the  running  of  more  careful  trial 
lines,  accompanied  by  a  transit  survey  for  location,  and  by  cross- 
sectioning  with  the  aid  of  a  couple  of  rodmen,  both  by  stadia  and 
level,  for  a  little  distance  to  either  side  of  the  line.  For  this  class 
of  work  a  plane-table  will  be  found  more  suitable  than  a  transit, 
since  on  it  can  be  sketched  contour  lines  as  the  work  progresses. 

From  the  end  of  the  diversion  lines  thus  developed  a  rough 
preliminary  level  and  transit  or  plane-table  line  should  be  run 
back  into  the  country,  approximately  on  a  grade  contour  line 
skirting  the  higher  slopes.  This  line  will  furnish  the  data  on 
which  to  estimate  approximately  the  area  of  land  controlled  by 
this  high-level  line.  These  facts  ascertained  and  the  relations 
of  the  amount  of  water,  its  duty  and  the  area  of  land  which  it  will 
irrigate,  and  the  total  area  under  command  having  been  deter- 
mined, trial  location  lines  may  be  run  in  similar  manner  for  the 
selection  of  the  final  main  line  and  its  branches.  The  combina- 
tion of  level  followed  up  for  location  by  transit  or  plane-table  with 
stadia  accompaniment  for  cross-sections  will  then  furnish  all  the 
details  for  final  location.  In  all  of  the  operations  thus  described 
substantial  bench-marks  should  be  established  as  frequently  as 
possible,  as  well  as  tie-points  for  the  horizontal  control.  When 
the  final  location  trial  lines  are  being  run,  more  permanent  bench- 
marks should  be  left  at  frequent  intervals,  and  in  the  course  of  all 


130  ALIGNMENT,    SLOPE,    AND    CROSS-SECTION 

the  surveys  connections  should  be  made  as  frequently  as  possible 
with  the  land-survey  system  of  the  country,  if  the  work  be  in  the 
western  United  States,  in  order  that  the  relations  of  the  irrigation 
project  and  various  lines  and  ditches  to  this  system  of  land  surveys 
and  the  surrounding  country  maybe  at  once  established  (Art.  141). 

140.  Contour  Topographic  Survey. — In  practically  all  cases 
where  the  time  and  means  at  the  disposal  of  the  engineer  will  per- 
mit, the  best  results  will  be  obtained  by  making  in  the  beginning 
a  detailed  contour  map  of  the  area  under  consideration.  In  nearly 
all  instances  it  will  be  best  to  precede  such  a  survey  by  a  hasty  trial 
level  line  or  two,  in  order  to  ascertain  the  feasibility  of  bringing 
the  water  to  the  lands,  and  the  area  that  will  be  commanded. 
These  questions  settled,  and  the  approximate  location  of  diversion 
lines  along  steep  hillsides  or  canyon  walls  having  been  ascertained, 
the  contour  survey  should  be  made  to  include  only  so  much  of  the 
diversion  line  as  is  in  question,  and  of  the  irrigable  area  as  will  lie 
below  the  high-line  levels. 

Where  the  location  of  the  diversion  line  is  fixed  by  the  rough- 
ness of  the  topography,  a  good  method  of  contour  survey  is  to 
run  out  a  couple  of  limiting  grade  contours  with  level  and  plane- 
table,  the  lower  being  at  the  lowest  possible  limit  of  diversion  line, 
and  the  upper  at  the  highest.  In  the  case  of  the  Santa  Ana  canal 
(Art.  148)  the  vertical  distance  between  these  two  was  found 
rarely  to  exceed  70  to  100  feet.  These  lines  should  be  run  in 
conjunction  with  stadia  cross-sectioning,  which  should  be  plotted 
directly  on  the  plane-table  sheet  on  a  scale  of  100  to  500  feet  to 
the  inch,  with  a  contour  interval  of  2  to  5  feet.  With  such  a  map 
the  engineer  may  be  able  to  lay  down  a  final  paper  location. 

Where  the  diversion  line  terminates  in  more  open,  gently 
sloping  country,  the  survey  of  the  irrigable  area  is  made  thus: 
Beginning  at  the  end  of  the  survey  for  diversion  line,  and  following 
around  on  the  approximate  high-line  grade,  a  careful  transit  and 
level  line  should  be  run  to  the  limits  of  the  highest  portions 
of  the  irrigable  area.  From  this  chained  transit  and  level 
lines  should  be  run  with  equal  accuracy  down  the  summits 
of  the  divides  or  interfluves  separating  the  main  drainage  lines, 
and  as  these  reach  the  lower  limits  of  the  area  under  examina- 


RIGHT    OF    WAY    ON    PUBLIC    LAND  131 

tion  they  should  be  connected  by  cross-lines.  The  whole  may 
then  be  plotted  on  a  suitable  scale,  say  500  to  1000  feet  to  one 
inch  and  in  5-  or  ic-foot  contours.  The  sheet  on  which  these 
lines  are  plotted  may  then  be  taken  into  the  field  either  as  a  whole 
or  divided  into  sections,  placed  on  plane-table  boards,  and  the 
topography  filled  in  thereon.  This  should  not  be  done  by  running 
out  the  various  contours,  but  by  irregularly  cross-sectioning  or 
dividing  up  the  area  by  lines  which  shall  so  cut  up  the  territory  as 
to  enable  the  contour  crossings  of  the  lines  run  on  the  plane-table 
to  be  connected  from  one  line  to  the  other  with  an  accuracy  well 
within  the  contour  interval,  and  thus  permit  of  the  whole  being 
filled  up  as  a  final  map.  This  secondary  work  resting  on  the 
main  chained  and  taped  lines  is  preferably  done  in  a  more  cheap 
and  expeditious  manner  by  using  the  plane-table  instead  of  the 
transit,  the  stadia  instead  of  the  chain  or  tape,  and  in  some  cases 
the  hand-level  or  vertical  or  gradienter  angles  in  place  of  the 
spirit-level,  though  the  former  methods  for  elevations  must  be 
adopted  and  used  with  the  greatest  precaution. 

On  such  a  map  it  then  becomes  an  easy  matter  to  lay  down 
the  approximate  location  of  the  main  canal  lines  and  their  various 
branches,  the  sites  of  falls,  regulating  works,  and  escapes.  There- 
after it  may  be  necessary,  prior  to  construction,  to  make  other 
more  detailed  contour  maps  of  limited  areas,  with  a  view  to 
determining  in  special  cases  the  more  exact  location  of  the  heads 
of  branches,  the  crossing  of  drainage  lines,  the  position  of  escapes, 
and  other  critical  points  on  the  canal  line. 

141.  Right  of  Way  on  Public  Land;  also  State  Desert-land 
Grants. — In  order  to  obtain  right  of  way  for  canals,  ditches,  or 
reservoirs  on  private  lands  in  the  West,  arrangements  must  be 
made,  as  elsewhere  in  the  United  States,  by  purchase  or  other- 
wise, with  the  owner.  To  obtain  right  of  way  on  public  lands, 
surveys,  maps,  and  construction  must  be  made  to  accord  with 
certain  regulations  of  the  General  Land  Office,  whereupon  a  grant 
of  the  land  affected  by  the  right  of  way  will  be  made.  This  grant, 
however,  is  only  for  purposes  of  canal  or  reservoir  construction, 
is  dependent  on  the  fulfillment  of  the  conditions  required,  and  is 
not  transferred  in  fee. 


132  ALIGNMENT,    SLOPE,    AND    CROSS-SECTION 

Among  other  of  the  requirements  which  must  be  fulfilled  that 
right  of  way  may  be  granted  are  the  following :  The  survey  in  all 
its  parts  must  be  connected  with  section  and  township  corners  of 
the  public-land  survey ;  especially  the  termini  of  the  canal,  ditch, 
or  lateral  must  be  connected  with  the  nearest  corner.  All  data 
for  the  computation  of  traverses  connecting  with  such  corners 
must  be  entered  in  the  field-notes.  The  method  of  running  the 
grade  lines  must  be  described,  as  well  as  the  size,  graduation,  and 
make  of  instrument  used.  Stations  and  courses  must  be  num- 
bered, and  field-notes  must  show  whether  the  side  or  middle  line 
of  the  canal  has  been  run.  Maps  for  filing  with  the  general  and 
local  land  offices  must  be  drawn  on  tracing-linen,  in  duplicate,  on 
the  scale  of  2000  feet  to  the  inch  for  canals  and  1000  feet  to  the 
inch  for  reservoirs,  or  on  a  larger  scale  in  special  cases.  These 
maps  should  show  all  subdivisions  of  the  public  surveys,  the  source 
and  amount  of  water-supply  of  the  reservoir  or  canal,  the  details 
of  alignment  of  canals,  and  flood  lines  of  reservoirs.  Permanent 
monuments  must  be  set  at  the  intersection  of  the  water-line  of  the 
reservoir  with  the  public-land  lines,  also  on  either  side  of  the  in- 
tersection of  the  canal  lines,  in  such  manner  as  to  comply  with  the 
requirements  of  witness  corners  as  laid  down  in  the  "  Manual  of 
Surveying  Instructions,"  issued  by  the  General  Land  Office  in 
1894.  The  map  must  also  bear  a  statement  of  the  width  of  each 
canal  or  branch  at  high-water  line,  the  capacities  of  reservoirs  in 
acre-feet,  and  height  of  proposed  dam.  They  must  also  show,  in 
ink  of  a  distinctive  color,  other  canals  or  reservoirs  than  those  for 
which  application  of  right  of  way  is  made.  In  addition  all  field- 
notes  must  be  in  duplicate,  properly  dated,  and  be  filed  like  the 
maps;  and  both  field-notes  and  maps  should  bear  the  certificates 
of  the  engineer  and  president  of  the  company  or  owner  of  the  canaL 

142.  Obstacles  to  Alignment. — Such  obstacles  as  streams, 
gullies,  ravines,  unfavorable  or  low-lying  soil,  or  rocky  barriers 
are  frequently  encountered  in  canal  alignment.  The  best  method 
of  passing  these  must  be  carefully  studied.  It  may  be  cheapest 
to  carry  the  canal  around  these  obstructions,  or  it  may  be  better 
at  once  to  cross  them  by  aqueducts,  flumes,  or  inverted  siphons, 
or  to  cut  or  tunnel  through  the  ridges.  Careful  study  should  be 


SIDEHILL    CANAL    WORK  133 

made  of  each  case,  and  estimates  made  of  the  cost  not  only  of  first 
construction,  but  of  ultimate  maintenance.  In  crossing  swamps 
or  sandy  bottom  lands  it  may  be  cheaper,  because  of  the  losses 
which  the  water  will  sustain  from  absorption,  to  carry  the  canal 
in  an  artificial  channel  through  such  places.  If  water  be  abun- 
dant, it  may  be  less  expensive  on  hillside  work  simply  to  build  the 
canal  with  an  embankment  on  its  lower  side,  permitting  the  water 
to  flood  back  on  the  upper  side  according  to  the  slope  of  the  coun- 
try. In  such  cases  the  losses  by  evaporation  and  absorption  will 
be  great  in  the  beginning,  but  ultimately  these  flat  places  may 
become  silted  up  and  a  permanent  channel  made  through  them. 
The  relative  cost  of  building  a  sidehill  canal  wholly  in  excavation 
or  partly  in  embankment  should  be  considered.  If  the  hillside 
is  steep  and  rocky,  the  advisability  of  tunnelling,  of  building  a 
masonry  retaining-wall  on  the  lower  side  of  the  canal,  or  of  carry- 
ing it  in  an  aqueduct  or  flume  will  have  to  be  considered. 

143.  Sidehill  Canal  Work. — It  is  extremely  difficult  to  carry 
a  large  canal  along  steep  sidehill  slopes.  To  get  a  sufficient 
cross-section  to  carry  the  volume  required  without  unduly 
increasing  the  velocity  demands  the  exercise  of  careful  judgment. 


FIG.  15. — Canal  Cross-sections  for  Varying  Bed-widths. 

It  is  possible  to  get  the  same  cross-sectional  area  by  employing 
different  proportions  of  depth  to  bed-width.  The  less  the  cross- 
sectional  area  of  a  channel,  the  less  its  cost  and  the  expense  for 
maintenance.  It  is  therefore  necessary  first  to  choose  the  highest 
possible  velocity  which  the  resistance  of  the  material  and  the 
necessity  of  commanding  land  will  permit,  and  then  to  give  the 
canal  such  a  cross-sectional  area  as  will  produce  the  required 
discharge.  The  great  difference  in  excavation  of  two  canals  of 
equal  capacity  but  different  proportions  of  bed-width  to  depth  is 


134  ALIGNMENT,    SLOPE,    AND    CROSS -SECTION 

graphically  shown  in  Fig.  15.  In  one  case  vastly  more  material 
will  have  to  be  moved  than  in  the  other,  while  the  surface  exposed 
to  evaporation  and  absorption  will  be  greatly  increased.  Where 
the  material  is  suitable  and  not  too  liable  to  cause  loss  by  percola- 
tion, it  is  well  to  equalize  the  cut  and  fill.  In  this  way  still  less 
material  will  have  to  be  moved,  for,  as  shown  in  the  illustration, 
the  depth  of  excavation  is  diminished  by  raising  the  lower  bank. 

144.  Curvature. — A   direct   or   straight   course   is   the   most 
economical  alignment,  as  it  gives  the  greatest  freedom  of  flow 
and  causes  the  least  erosion  of  the  banks.     It  also  greatly  dimin- 
ishes the  cost  of  construction  and  the  losses  by  absorption  and 
evaporation  consequent  on  the  increased  length  of  a  less  direct 
location.     It  is  an  error  in  alignment  to  adhere  too  closely  to 
grade  lines  following  the  general  contour  of  the  country.     By  the 
insertion  of  an  occasional  fall  it  is  frequently  possible  to  obtain 
a  more  desirable  location  and  to  diminish  the  cost  of  construc- 
tion by  the  avoidance  of  some  natural  obstacle. 

One  of  the  most  serious  errors  in  alignment  is  the  careless 
location  of  curves,  to  which  detail  too  little  attention  is  ordinarily 
paid.  The  insertion  of  sharp  bends  inevitably  results  m  the 
destruction  of  the  canal  banks,  or  requires  that  they  shall  be 
paved  or  otherwise  protected  to  prevent  their  erosion.  On  the 
other  hand  instances  have  been  noted  where  engineers  have 
inserted  great  curves  carefully  constructed  on  some  fixed  radius 
of  absurd  length,  as  though  the  canal  were  a  railway  line.  Curv- 
ature diminishes  the  delivering  capacity  of  the  canal,  and  too 
sharp  a  curve  endangers  the  structure  itself.  In  large  canals  of 
moderate  velocity  it  will  be  safe  in  most  cases  to  take  the  radius 
of  curvature  at  from  three  to  five  times  the  bed  width  of  the 
canal.  As  the  cross-section  becomes  smaller  or  the  velocity  is 
increased,  the  radius  of  curvature  should  be  correspondingly 
increased.  To  keep  up  the  discharge  of  a  canal  either  its  cross- 
section  or  grade  should  be  increased  in  proportion  to  the  sharp- 
ness of  the  curve. 

145.  Borings,  Trial-pits,  and  Permanent  Marks. — In  finally 
locating   an   expensive  work,   borings   and   trial-pits  should  be 
made,  the  former  with  a  light  steel  rod  and  the  latter  by  simple 


EXAMPLE     OF     CANAL    ALIGNMENT  135 

excavation,  in  order  to  discover  the  character  of  the  material  to 
be  encountered.  In  making  the  final  survey  of  a  canal  it  is  well 
to  place  at  convenient  intervals  permanent  bench-marks  of  stone 
or  other  suitable  material.  The  establishment  of  these  along 
the  side  of  the  canal  in  some  safe  place  will  give  convenient  datum 
points  to  which  levels  can  be  referred  whenever  it  may  be  neces- 
sary to  make  repairs  or  run  branch  lines.  Mile  or  quarter-mile 
pests  or  permanent  stakes  should  also  be  set  in  the  canal  banks 
so  that  future  surveys  and  changes  in  the  line  may  be  referred  to 
these. 

146.  Example  of  Canal  Alignment. — Ganges  Canal. — An 
excellent  example  of  a  typical  alignment  on  one  of  the  great 
Indian  canals  is  that  of  the  Ganges  canal,  which  heads  in  the 
Ganges  River  at  Hurdwar,  where  the  stream  issues  suddenly 
from  between  the  foothills  of  the  Himalayas  on  to  the  broad 
level  plains.  In  the  first  twenty  miles  of  its  course  the  canal 
encounters  considerable  sub-Himalayan  drainage,  and  the 
works  for  the  passage  of  this  and  for  the  reduction  of  slope 
in  the  canal  by  means  of  falls  are  important  (PI.  I).  The  slope 
of  the  river-bed  and  country  averages  from  8  to  10  feet  per  mile. 

At  the  site  of  the  headworks  the  river  is  divided  into  several 
channels,  one  of  which,  about  300  feet  in  width,  follows  the 
Hurdwar  shore  and  rejoins  the  main  stream  half  a  mile  below 
that  town.  As  the  discharge  of  the  canal  is  6700  second-feet 
and  that  of  the  river  never  falls  below  8000  second-feet,  only 
a  portion  of  the  water  is  required  at  any  time.  This  is  diverted 
to  the  Hurdwar  channel  by  means  of  training  works  and  tem- 
porary bowlder  dams,  and  the  current  has  deepened  the  chan- 
nel until  it  now  has  a  uniform  slope  of  yj  feet  per  mile  to  the 
canal  head.  The  regulator  is  about  half  a  mile  below  the  first 
training  works,  and  consists  of  a  weir  and  scouring  sluices  across 
the  channel.  In  the  first  few  miles  the  canal  crosses  several 
minor  streams  .which  are  admitted  by  means  of  inlets.  At  the 
sixth  mile  it  is  crossed  by  the  Ranipur  torrent,  which  is  passed 
over  it  in  a  masonry  superpassage  195  feet  in  breadth  (PI.  XVII). 
In  the  tenth  mile  the  Puthri  torrent,  having  a  catchment  basin  of 
about  eighty  square  miles,  or  twice  that  of  the  Ranipur,  is  carried 


136  ALIGNMENT,    SLOPE,    AND    CROSS-SECTION 

across  the  canal  by  a  similar  superpassage  296  feet  in  breadth. 
The  sudden  flood  discharges  in  these  torrents  are  of  great  vio- 
lence, the  Puthri  discharging  as  much  as  15,000  second-feet  and 
having  a  velocity  of  about  1 5  feet  per  second. 

In  the  thirteenth  mile  the  canal  encounters  the  Rutmoo  tor- 
rent (Article  232),  which  has  a  slope  of  8  feet  per  mile  and  a 
catchment  basin  half  as  large  again  as  that  of  the  Puthri.  This 
torrent  is  admitted  into  the  canal  at  its  own  level,  and  in  the  side 
of  the  canal  opposite  to  the  inlet  is  an  open  masonry  outlet  dam 
or  set  of  escape  sluices.  Just  below  this  level  crossing  is  a  regu- 
lating bridge  by  which  the  discharge  of  the  canal  can  be  readily 
controlled;  thus  in  time  of  flood,  by  opening  the  sluices  in  the 
outlet  dam  and  adjusting  those  in  the  regulator  so  as  to  admit 
into  the  canal  the  volume  of  water  required,  the  remainder  is 
discharged  through  the  scouring  sluices,  whence  it  continues  in 
its  course  down  the  current. 

In  the  nineteenth  mile,  near  Roorkee,  the  canal  crosses  the 
Solani  River  and  valley  on  an  enormous  masonry  aqueduct  (Arti- 
cle 239).  The  Solani  River  in  times  of  highest  flood  has  a  dis- 
charge of  35,000  second-feet  "and  the  fall  of  its  bed  is  about  5  feet 
per  mile.  The  total  length  of  the  aqueduct  is  920  feet.  The 
banks  of  the  canal  on  the  up-stream  side  are  revetted  by  means 
of  masonry  steps  for  a  distance  of  10,713  feet,  and  on  the  down- 
stream side  for  a  distance  of  2722  feet.  For  i f  miles  the  bed 
of  the  canal  is  raised  on  a  high  embankment  previously  to  its 
reaching  the  aqueduct,  and  for  a  distance  of  half  a  mile  below  it 
is  on  a  similar  embankment.  The  greatest  height  of  the  canal- 
bed  above  the  country  is  24  feet  (PL  XVI).  The  aqueduct 
proper  consists  of  fifteen  arches  of  50  feet  span  each.  In  addi- 
tion to  these  great  works  there  are  in  the  first  twenty  miles  of  the 
canal  five  masonry  works  for  damming  minor  streams  and  a 
number  of  masonry  falls. 

Beyond  Roorkee  the  main  canal  follows  the  high  divide 
between  the  Ganges  and  the  west  Kali  Nadi,  and  continues  in 
general  to  follow  the  divide  between  the  Ganges  and  the  Jumna 
rivers  to  Gopalpur,  a  short  distance  below  Aligarh,  where  the 
main  canal  bifurcates,  forming  the  Cawnpur  and  Etawah  branches. 


EXAMPLE    OF    CANAL    ALIGNMENT 


137 


PLATE  i. — Plan  and  Cross-section  of  Ganges  Canal,  Hurdwar  to  Roorkee,  India. 


138  ALIGNMENT,    SLOPE,    AND    CROSS-SECTION 

The  former  tails  into  the  Ganges  River  at  Cawnpur  and  is  170 
miles  in  length.  The  Etawah  branch  is  also  170  miles  long  and 
tails  into  the  Jumna  River  near  Humerpur.  The  Vanupshahr 
branch  leaves  the  main  line  at  the  fiftieth  mile,  and  flows  past 
the  towns  of  Vanupshahr  and  Shahjahanpur.  It  formerly  ter- 
minated at  mile  82  J,  emptying  into  the  Ganges  River;  but  it  is 
now  continued  to  a  point  near  Kesganj,  where  it  tails  into  the 
Lower  Ganges  canal.  The  first  main  distributaries  are  taken 
from  both  sides  of  the  canal  a  short  distance  below  Roorkee. 
The  nature  of  the  country  offers  abundant  facilities  for  escapes 
from  the  canals,  of  which  five  are  constructed  on  the  main  line, 
four  at  the  Cawnpur  branch,  and  three  on  the  Etawah  branch, 
besides  numerous  small  escapes  to  the  distributaries. 

147.  Example  of  Canal  Alignment — Turlock  Canal. — A  typical 
American  canal  alignment  is  that  of  the  Turlock  canal,  which 
is  diverted  from  the  Tuolumne  River  in  California  at  a  point 
where  it  emerges  from  the  Sierras  between  high  rocky  canyon 
walls.  For  the  first  five  miles  the  canal  is  built  along  steeply 
sloping  hillsides,  and  it  crosses  numerous  drainage  channels  in 
its  endeavors  to  surmount  the  bluffs  bordering  the  river  and  gain 
the  irrigable  lands.  The  topography  is  so  irregular  that  the  first 
attempts  which  were  made  at  diversion  were  unsuccessful.  The 
present  location  was  discovered  only  after  a  careful  contour  topo- 
graphic map  had  been  made  of  the  entire  region,  and  from  this 
the  canal  line  was  laid  down  (Fig.  16). 

The  headworks  of. the  Turlock  canal  consist  of  a  masonry 
dam  which  is  constructed  as  a  common  diversion  weir  for  the 
Turlock  canal  and  the  canal  of  the  Modesto  irrigation  district, 
which  latter  heads  on  the  opposite  or  north  bank  of  the  river. 
This  weir  (Article  356)  is  located  between  high  canyon  walls, 
two  miles  above  the  town  of  La  Grange,  at  a  point  where  the 
abutments  and  foundation  of  the  weir  consist  of  firm  homogene- 
ous dioritic  basalt,  in  which  scarcely  any  excavation  is  required. 
The  canal  is  diverted  from  the  south  bank  of  the  river  at  a  point 
about  50  feet  above  the  end  of  the  main  weir.  Owing  to  the 
great  floods  which  occur  in  this  narrow  canyon  the  water  may 
rise  as  much  as  15  feet  in  an  hour,  and  the  maximum  height  which 


EXAMPLE    OF    CANAL    ALIGNMENT 


139 


it  is  estimated  to  reach  above  the  sill  of  the  canal  is  16  feet.  The 
pressure  of  this  height  of  water  on  the  regulator  head  would  be 
so  great  as  materially  to  increase  the  cost  of  its  construction. 
Accordingly  the  canal  heads  in  a  tunnel  560  feet  in  length,  blasted 
through  the  rock  of  the  canyon  walls,  and  having  no  regulating 
apparatus  at  its  entrance.  Where  it  discharges  into  the  open 


Main 


FIG.  1 6. — Turlock  Canal.     Plan  of  Diversion  Line. 

cut,  which  is  the  commencement  of  the  canal,  regulating  gates 
and  scouring  or  escape  sluices  are  placed.  The  entrance  tunnel 
is  12  feet  wide  at  the  bottom,  5  feet  in  height  to  the  spring  of  the 
arch,  above  which  it  is  semicircular  with  a  6-foot  radius.  Its 
slope  is  24  feet  per  mile,  and  it  is  excavated  in  a  firm  dioritic  rock 
which  requires  no  lining.  The  regulator  in  the  canal  head  below 
the  exit  of  the  tunnel  consists  of  six  gates,  each  3  feet  wide  in  the 


140 


ALIGNMENT,    SLOPE,    AND    CROSS-SECTION 


clear  and  12  feet  irf  height.  These  gates  are  constructed  of  tim- 
ber and  iron,  and  slide  on  angle-iron  bearings  let  into  the  rock 
and  firmly  set  in  concrete.  The  escape  is  set  at  right  angles  to 
the  canal-line  heading  immediately  above  the  regulator,  between 
it  and  the  end  of  the  tunnel,  and  tailing  back  into  the  Tuolumne 
River  a  short  distance  below  the  subsidiary  weir.  Like  the  regu- 
lator, the  escape  consists  of  six  gates,  each  3  feet  wide  in  the  clear, 
12  feet  high,  and  constructed  of  similar  material  and  in  like  man- 
ner. It  is  estimated  that  whereas  a  maximum  flood  of  16  feet 


FIG.  17.— Turlock  Canal.     View  of  Sidehill  Work. 

over  the  sill  of  the  tunnel  will  give  a  discharge  in  front  of  the  reg- 
ulator and  escape  of  about  4000  second-feet  with  a  velocity  of 
20  feet  per  second,  the  wasting  capacity  of  the  escape  will  be  at 
least  6000  second-feet,  thus  fully  insuring  the  canal  against  acci- 
dent from  this  source. 

Below  the  regulating  gates  the  main  canal  proper  begins, 
having  a  capacity  of  1500  second-feet.  For  the  first  6200  feet 
it  is  excavated  in  slate  rock  on  a  steep  hillside  (Fig.  17).  It  has 
a  bed  width  of  20  feet,  depth  of  water  10  feet,  the  upper  rock 
slope  being  J  to  i,  while  the  lower  bank  or  downhill  slope,  where 
gullies  are  crossed,  is  built  up  with  an  inner  slope  of  J  to  i  and  is 
faced  with  18  inches  of  dry-laid  retaining-wall  inside  and  outside, 


EXAMPLE     OF    CANAL    ALIGNMENT  141 

the  interior  of  the  bank  consisting  of  a  well-puddled  earth  core 
12  feet  in  top  width  (Fig.  21).  Where  this  portion  of  the  canal 
is  on  ordinary  sloping  ground,  not  crossing  gulches,  its  dimen- 
sions are  the  same,  but  the  inner  face  only  has  the  18  inches  of 
riprapping,  the  downhill  slope  of  the  bank  consisting  of  dirt  and 
other  soil.  The  top  width  of  the  bank  in  such  places  is  5  feet 
and  the  puddle  wall  5  feet  in  thickness.  This  portion  of  the  canal 
line  has  a  grade  of  7.92  feet  per  mile,  which  gives  a  velocity  of  7^ 
feet  per  second.  After  the  second  year  this  slate-rock  so  disin- 
tegrated by  air-slacking  that  much  of  it  fell  away,  and  the  sides 
of  the  cutting  caved  in,  requiring  extensive  rebuilding  on  firmer 
lines  and  flatter  slopes. 

At  the  end  of  this  slate-rock  work  the  canal  empties  into  Snake 
ravine,  up  which  the  water  of  the  canal  runs  for  940  feet.  This 
was  effected  by  constructing  an  earth  dam  across  the  mouth  of  the 
ravine  just  below  the  entrance  of  the  canal,  which  raises  the  sur- 
face of  the  water  so  as  to  form  a  small  settling  reservoir  and  pro- 
duces a  flow  up  the  course  of  the  ravine  for  the  distance  above 
mentioned.  The  earth  dam  is  20  feet  wide  on  top,  318  feet  long 
on  the  crest,  with  slopes  of  2  to  i  and  a  maximum  height  of  52 
feet.  This  dam  was  partly  constructed  of  material  borrowed 
from  its  abutments  and  the  canal  excavation  and  partly  by  a 
silting  process  from  material  washed  out  of  a  hydraulic  cut  at 
the  upper  end  of  the  ravine.  This  hydraulic  cut,  which  is  utilized 
as  the  canal  bed,  is  800  feet  in  length  and  45  feet  in  maximum 
height,  with  slopes  of  i  to  i  and  a  grade  of  5  feet  per  mile.  Owing 
to  the  abundance  of  water  procurable  this  cut  was  more  cheaply 
excavated  by  the  hydraulic  process  than  it  could  have  been  by 
other  means.  At  the  far  end  of  the  cut  the  canal  enters  an  old 
hydraulic  washing  which  is  utilized  for  its  channel  for  a  length  of 
2380  feet,  after  which  it  enters  a  rock  cut  860  feet  long,  with  a 
maximum  depth  of  45  feet  and  a  similar  cross-section  to  the  cut 
first  described. 

At  the  end  of  this  rock  cut  the  canal  water  is  discharged  into 
Dry  creek,  down  which  it  flows  for  a  distance  of  6500  feet  on  a 
grade  of  12  feet  to  the  mile,  and  from  which  it  is  diverted  by 
means  of  an  earth  dam  460  feet  long.  This  dam  has  a  maxi- 


142  ALIGNMENT,    SLOPE,    AND    CROSS-SECTION 

mum  height  of  23  feet  with  side  slopes  of  3  to  i,  and  is  riprapped 
to  a  depth  of  3  feet  on  its  upper  face.  At  its  south  end  the  dam 
abuts  on  sandstone  rock  in  which  a  wasteway  is  cut  50  feet  widlw 
with  its  sill  4  feet  below  the  crest  of  the  dam,  and  which  will  dis- 
charge back  into  the  creek  180  feet  below  the  toe  of  the  dam. 
Between  the  wasteway  and  the  end  of  the  dam  is  a  waste-gate 
which  it  is  intended  shall  be  used  in  the  time  of  freshets,  for  Dry 
creek  has  a  maximum  discharge  of  4000  second-feet  and,  as  the 
freshets  are  quick  and  violent,  a  large  wasting  capacity  is  neces- 
sary. These  waste-gates  are  ten  in  number,  each  3  feet  wide  in 
the  clear  and  10  feet  in  depth.  They  fall  automatically  outward 
or  down-stream,  being  hinged  at  the  bottom  to  a  concrete  floor 
laid  on  the  bed-rock,  and  when  raised  they  are  attached  by  chains 
to  the  piers. 

For  about  a  mile  below  Dry  creek  the  canal  is  excavated  in 
heavy,  sandy  loam,  in  which  it  has  a  bed  width  of  30  feet,  with 
slopes  2  to  i,  a  depth  of  10  feet,  and  a  grade  of  ij  feet  per  mile. 
At  the  end  of  this  excavation  the  canal  crosses  Dry  creek  in  a 
flume  62  feet  in  height  and  450  feet  long,  after  crossing  which 
the  canal  enters  a  series  of  three  tunnels,  the  cross-sections  of 
which  are  nearly  similar  to  that  of  the  first  tunnel,  while  they  are 
excavated  in  a  tufa  and  sandstone  which  will  require  no  timber- 
ing. The  first  tunnel  is  211  feet  in  length,  the  second  400  feet, 
and  the  third  400  feet  in  length,  while  they  are  separated  by  short, 
open  cuts  excavated  in  hardpan  and  clay,  which  are  respectively 
250  and  300  feet  in  length.  The  last  tunnel  discharges  into 
Delaney  gulch,  which  is  crossed  by  constructing  a  high  bank  or 
earth  dam  below  the  canal,  the  total  length  of  which  is  180  feet, 
its  maximum  height  being  40  feet  and  its  top  width  20  feet.  The 
volume  of  discharge  of  this  gulch  is  so  trifling  that  it  was  unneces- 
sary to  provide  a  wasteway  or  escape  at  this  point.  Immediately 
after  crossing  the  gulch  the  canal  enters  a  cut  8  feet  in  maximum 
depth,  with  the  same  cross-section  and  grade  as  the  first  cut  and 
having  a  length  of  3300  feet.  The  canal  is  then  widened  to  a  bed 
width  of  35  feet  and  depth  of  10  feet,  and  is  given  a  grade  of  i 
foot  per  mile.  At  the  end  of  a  mile  and  a  half  Peasley  creek  is 
crossed  on  a  trestle  and  flume  60  feet  in  height  and  360  feet  long, 


EXAMPLE    OF    CANAL    ALIGNMENT  143 

the  waterway  on  which  is  20  feet  wide  and  7  feet  in  depth.  This 
flume  is  provided  with  an  escape  constructed  in  its  bottom  and  dis- 
charging into  two  small  sloping  flumes  which  lead  the  water  down 
into  the  bed  of  Peasley  creek  (Article  215). 

At  the  end  of  the  flume  the  main  canal  is  reached  and  traversed 
for  a  distance  of  1 1  miles,  in  which  are  two  rock  cuts,  each  3000 
feet  long  and  respectively  20  and  30  feet  wide  on  the  bottom, 
depth  of  water  yj  feet,  and  grade  5  feet  per  mile.  The  remainder 
of  this  length  of  the  canal  varies  in  cross-section  according  to  the 
soil,  but  most  of  it  has  a  bottom  width  of  70  feet  and  depth  of 
water  of  7^  feet,  slopes  2  to  i,  and  a  grade  of  i  foot  per  mile. 

The  main  canal  as  outlined  above  consists  for  the  18  miles  of 
its  length  of  a  purely  diversion  channel,  the  object  of  which  is  to 
bring  the  water  to  the  irrigable  lands  included  within  the  area  of 
the  Turlock  district.  At  the  terminus  of  this  diversion  line  the 
canal  begins  at  once  to  do  duty  by  watering  the  lands,  and  below 
this  point  the  main  line  is  divided  into  four  main  branches,  each 
of  which  has  a  bottom  width  of  30  feet,  depth  of  water  5  feet,  and 
grade  of  2  feet  per  mile,  their  aggregate  length  being  80  miles. 
In  addition  to  these  main  branches  minor  distributaries,  having 
a  total  length  of  180  miles,  lead  the  water  to  each  section  of  land. 
The  discharge  of  the  branches  is  so  designed  as  to  give  a  uniform 
velocity  of  2^  feet  per  second,  in  order  that  any  matter  carried  in 
suspension  will  be  held  up  until  deposited  on  the  agricultural 
lands  instead  of  in  the  canals. 

148.  Examples  of  Canal  Alignment,  Santa  Ana  Canal. — A 
typical  American  alignment  is  that  of  the  Santa  Ana  canal, 
diverted  from  the  Santa  Ana  River  above  the  head  of  the  San 
Bernardino  valley,  California.  This  canal  is  interesting  because 
of  the  care  exercised  in  making  the  preliminary  and  location 
surveys  for  the  difficult  diversion  line  and  for  some  interesting 
details  of  construction,  chiefly  in  the  flumes,  siphons,  and  sand- 
boxes. 

The  Santa  Ana  canal  is  designed  to  irrigate  45,000  acres  in 
the  northern  part  of  San  Jacinto  valley,  which  is  separated  from 
the  canal  head  by  four  main  divides  between  the  Santa  Ana  River, 
Mill  creek,  Yucaipe,  Timoteo,  and  San  Jacinto  creeks.  Through 


144  ALIGNMENT,    SLOPE,   AND    CROSS-SECTION 

a  low  neck  in  the  higher  ridge  immediately  north  of  San  Jancinto 
valley  the  irrigating  company  had  previously  built  Moreno  tun- 
nel, 2320  feet  in  length,  and  of  the  capacity  desired.  This  tunnel 
had  been  well  lined  with  brick  and  plastered  with  cement  and 
therefore  became  a  controlling  factor  in  the  location  of  the  align- 
ment from  the  headworks  chosen.  The  source  of  water-supply 
is  the  natural  flow  of  the  Santa  Ana  River  reinforced  by  the  Bear 
valley  storage  reservoir  in  the  San  Bernardino  mountains.  The 
country  between  the  tunnel  and  the  point  at  which  the  Santa  Ana 
River  leaves  the  mountains  in  a  canyon  at  an  elevation  of  1850  feet 
is  exceedingly  broken.  The  air-line  between  these  two  points  is 
12  miles,  while  a  grade  contour  connecting  them  would  be  42  miles 
in  length. 

The  site  of  the  headworks  is  in  a  solid  rock  point  of  the  canyon 
side  where  the  river-bed  has  an  elevation  of  2320  feet.  The 
diversion  line  was  designed  to  carry  240  second-feet  of  water  for 
the  first  portion  of  the  line,  and  thereafter  300  second-feet  to  a 
reservoir  site  on  the  line  of  the  work,  after  which  it  will  diminish 
to  200  second-feet  to  the  Moreno  tunnel,  so  that  the  latter  figure 
represents  the  maximum  volume  which  will  be  carried  for  direct 
irrigation. 

The  intake  of  the  canal  is  a  tunnel  220  feet  in  length  through 
a  vertical  point  of  rock.  The  tunnel  debouches  at  a  point  where 
a  side  canyon  enters,  and  to  avoid  this  the  canal  is  built  into  the 
hill  as  a  walled  cutting,  over  which  the  side  torrent  is  carried. 
From  this  point  the  canal  rapidly  "  climbs  "  the  cliffs  and  mountain 
sides,  for  the  canyon  bed  drops  away  at  the  rate  of  125  to  1 60  feet 
a  mile,  and  on  its  line  the  tunnels,  flumes,  and  pipes  are  given 
hydraulic  gradients  averaging  less  than  10  feet  per  mile.  In  the 
course  of  this  line  nine  spurs  are  pierced  by  tunnels  having  an 
aggregate  length  of  4329  feet;  three  canyons  are  crossed  by 
pressure  pipes  or  siphons  having  a  total  horizontal  length  of  2127 
feet;  there  are  sixteen  stretches  of  flume  having  an  aggregate 
length  of  14,100  feet;  one  piece  of  walled  canal  152  feet  in  length; 
and  eight  masonry  walled  structures,  as  sand  gates,  junction  bays, 
and  escapes,  having  a  length  of  213  feet.  In  addition  there  are 
thirty-nine  structures  in  the  nature  of  trussed  girders  or  combina- 


10 


146  ALIGNMENT,    SLOPE,    AND    CROSS-SECTION 

tion  Fink  truss  spans  resting  on  timbers,  piers,  and  masonry 
footings  with  an  aggregate  length  of  3345  feet,  besides  which  there 
are  eight  stretches  of  canal  having  a  total  length  of  8214  feet, 
lined  with  rubble  in  mortar.  The  largest  stream  encountered  on 
the  completed  part  of  the  diversion  line  is  Mill  creek,  which  is 
crossed  in  a  flume  carried  on  a  steel  bridge  1072  feet  in  length 
(Plate  II). 

The  tunnels  are  sometimes  in  solid  rock,  when  only  the  water 
channel  is  masonry-lined  to  produce  a  smooth  surface,  and  at 
other  times  in  loose  material,  when  the  entire  surface  is  lined. 
These  tunnels  are  5  feet  9  inches  in  maximum  height,  and  5  feet 
3  inches  wide,  with  a  curved  invert  below  and  an  arched  roof 
above.  The  walled  canal  has  a  cross-section  practically  the  same 
as  the  water  channel  of  the  tunnel.  The  lined  canal  has  a  peculiar 
cross-section,  the  essential  point  of  which  is  similar  to  that  of  the 
tunnel  and  the  flumes,  namely,  an  unusual  depth  in  proportion  to 
width  (Fig.  21).  The  flumes  are  of  wood  and  of  the  kind  which 
may  be  called  the  stave  and  binder  combination,  consisting  of 
wood  bound  together  and  held  in  a  rounded  bottom,  straight- 
sided  form,  by  steel  ribs  and  binding  rods,  acting  in  conjunction 
with  wooden  yokes  or  ties  across  the  top  (Plate  III).  The  pipe 
lines  and  inverted  siphons  are  likewise  of  wood,  and  are  con- 
structed of  staves  2  inches  in  thickness,  52  inches  internal  di- 
ameter, with  carrying  capacities  each  of  120  second-feet,  two 
parallel  pipe  lines  being  used  on  the  main  line,  and  they  are  of  the 
common  wooden  stave  and  circular  binder-rod  pattern  (Art. 233). 
The  first  sand-box  or  escape  bay  (Fig.  82)  is  located  700  feet  from 
the  initial  point,  while  others  are  planned  for  different  points 
lowrer  down  on  the  works,  should  such  prove  necessary.  This 
first  sand-box  is  60  feet  long  by  13  feet  wide,  and  its  lower  end 
slopes  transversely  so  that  it  is  7.3  inches  deep  on  the  upper  side 
and  10.6  deep  on  the  lower  or  discharging  side,  and  it  is  so  con- 
structed as  to  cause  a  slacking  of  the  velocity  and  settlement  of 
sediment  at  this  point.  There  are  six  wasteways  or  escapes  in 
that  portion  of  the  diversion  line  which  is  now  built — four  at  the 
upper  ends  of  tunnels  3,  4,  5,  and  6  respectively,  and  at  distances 
of  3200,  6350,  8840,  and  1 2, 930  feet  from  the  intake. 


X 


yi 


148 


ALIGNMENT,     SLOPE,    AND    CROSS-SECTION 


149.  Velocity,  Slope,  and  Cross-section. — One  of  the  first 
considerations  in  designing  a  canal  system  is  the  quantity  of 
water  which  the  main  line  and  its  branches  are  severally  to  carry. 
This  is  chiefly  dependent  on  the  areas  which  they  will  command 
and  the  water  duty.  These  determined,  the  alignment  and 
construction  are  affected  most  by  the  slopes  and  cross-sections 
necessary  to  discharge  the  quantities  required  at  given  velocities. 
The  three  factors,  velocity,  slope,  and  cross-section,  are  nearly 
related  and  are  interdependent  one  upon  the  other.  Having 


FIG.  18. — Tunnel  Portal  and  Lining  Truckee-Carson  Canal,  Nevada. 

determined  the  discharge  required,  the  carrying  capacity  for 
this  quantity  can  be  obtained  by  increasing  the  slope  and  con- 
sequent velocity  and  diminishing  the  cross-sectional  area;  or 
by  increasing  the  cross-sectional  area  and  diminishing  the  velo- 
city. The  determination  of  the  proper  relation  of  cross-section 
to  slope  requires  the  exercise  of  considerable  judgment.  If  the 
material  in  which  the  excavation  is  to  be  made  will  permit,  it  is 
well  to  give  a  high  velocity,  as  the  deposition  of  silt  and  the  growth 


LIMITING    VELOCITY  149 

of  weeds  are  thus  reduced  to  a  minimum.  A  steep  slope  may 
result,  however,  in  bringing  the  canal  to  the  irrigable  lands  at 
such  an  elevation  that  it  will  not  command  the  desired  area. 
Again,  it  may  be  inadvisable  to  give  too  great  a  cross-section  if 
the  construction  is  in  sidehill  or  in  rock,  or  other  material  which 
is  expensive  to  remove.  Other  things  being  equal,  the  correct 
relation  of  slope  to  cross-section  is  that  in  which  the  velocity  will 
neither  be  too  great  nor  too  slow,  and  yet  the  amount  of  material 
to  be  removed  will  be  reduced  to  a  minimum.  Where  the  fall 
will  permit,  the  slope  of  the  bed  of  the  main  canal  should  be  less 
than  that  of  the  branches,  which  should  be  less  than  that  of  the 
distributaries  and  laterals,  the  object  being  to  secure  a  nearly 
uniform  velocity  throughout  the  system,  so  that  sedimentary 
matter  carried  in  suspension  may  not  be  deposited  until  the  irri- 
gable lands  are  reached. 

150.  Limiting   Velocity. — In    order    that    the    proper    slope 
may  be  chosen,  one  which  will  produce  a  velocity  that  shall  not 
cause  silt  to  be  deposited  on  the  one  hand,  or  erode  the  banks  on 
the  other,  the  amount  of  such  velocities  for  different  soils  should 
be  known.     In  a  light,  sandy  soil  it  has  been  found  that  a  surface 
velocity  of  from  2.3  to  2.4  feet  per  second,  or  mean  velocities  of 
1.85  to  1.93  feet  per  second,  give  the  most  satisfactory  results. 
It  has  been  discovered  that  velocities  of  from  2  to  3  feet  per  sec- 
ond  are  ordinarily  sufficiently  swift  to  prevent  the  growth  of 
weeds  or  the  deposition  of  silt,  and,  other  things  being  equal, 
this  velocity  is  the  one  which  it  is  most  desirable  to  attain.     In 
ordinary  soil  and  firm  sandy  loam  velocities  of  from  3  to  3^  feet 
per  second  are  safe,  while  in  firm  gravel,  rock,  or  hardpan  the 
velocity  may  be  increased  to  from  5  to  7  feet  per  second.     It  has 
been  found  that  brickwork  or  heavy  dry-laid  paving  or  rubble 
will  not  stand  velocities  higher  than  15  feet  per  second,  and  for 
greater  velocities  than  this  the  most  substantial  form  of  masonry 
construction  should  be  employed. 

151.  Grades  for  Given  Velocities. — The  grade  required  to 
give  these  velocities  is  chiefly  dependent  on  the  cross-sectional 
area  of  the  channel     Much  higher  grades  are  required  in  small 
than  in  large  canals  to  produce  the  same  velocity.     The  velocity 


150  ALIGNMENT,     SLOPE,     AND    CROSS-SECTION 

which  is  required  being  known,  the  grade  can  be  ascertained 
from  Kutter's  or  some  similar  formula.  In  large  canals  of  60 
feed  bed  width  or  upwards,  and  in  sandy  or  light  soil,  grades  as 
low  as  6  inches  in  a  mile  produce  as  high  velocities  as  the  material 
will  stand.  In  more  firm  soil  this  grade  may  be  increased  to 
from  12  to  1 8  inches  to  the  mile,  whereas  smaller  channels  will 
stand  slopes  of  from  2  to  5  feet  per  mile,  according  to  the  material 
and  dimensions  of  the  channel. 

152.  Examples  of  Canal  Velocities  and  Grades. — On  the 
Ganges  canal,  the  bottom  width  of  which  is  170  feet  and  the 
depth  7  feet,  a  slope  of  14  inches  per  mile  given  in  sandy  soil  pro- 
duces such  a  velocity  that  the  current  just  ceases  to  cut  the  bank 
or  to  deposit  silt,  showing  that  this  is  the  correct  slope  for  that 
canal  and  material.  In  another  portion  of  the  same  canal  slopes 
of  from  15  to  17  inches  have  been  found  too  great,  and  much 
damage  has  been  done  to  the  banks.  A  velocity  of  3  feet  per 
second  given  to  the  Soane  canal  is  found  too  great  for  the  mate- 
rial, as  much  damage  was  caused  by  erosion.  Careful  observa- 
tions of  the  slope  on  the  Ganges  canal  show  that  a  current  appar- 
ently perfectly  adjusted  to  light,  sandy  soil  was  produced  by  a 
surface  velocity  of  about  2.4  feet  per  second,  or  a  mean  velocity 
of  about  1.9  feet  per  second.  In  one  of  the  distributaries  in 
sandy  soil  having  some  clay  in  it  a  mean  velocity  of  1.93  feet  per 
second  caused  slight  deposits  of  silt,  but  did  not  permit  the  growth 
of  weeds.  On  the  western  Jumna  canal  silt  was  deposited  in 
small  quantities  with  a  velocity  of  from  2  to  2.75  feet  per  second, 
while  in  sandy  soil  the  latter  velocity  was  the  highest  permissible 
for  non-cutting  of  the  banks. 

In  the  light,  sandy -loam  soils  of  the  San  Luis  valley  in  Colo- 
rado, a  slope  of  6  inches  to  the  mile  given  on  the  Citizens'  canal 
has  proven  very  satisfactory.  So  low  a  slope  as  this  is  possible, 
because  the  water  is  comparatively  free  of  silt  and  there  is  little 
chance  of  its  deposition,  while  the  temperature  is  so  low  that 
there  is  little  likelihood  of  the  growth  of  weeds  affecting  the  canal 
bed.  Perhaps  the  highest  grade  on  any  canal  is  that  on  a  short 
portion  of  the  Del  Norte  canal  in  Colorado,  where  the  fall  is  35 
feet  per  mile  through  a  rock-cut.  On  several  miles  of  this  canal 


CROSS-SECTIONS  151 

the  grade  is  8  feet  per  mile,  but  after  it  reaches  the  earth  soil  in 
the  valley  it  is  reduced  to  i  in  2112. 

On  the  Interstate  canal,  Wyo.-Neb.,  built  by  the  Reclama- 
tion Service,  with  a  bed  width  of  34  feet  and  depth  of  10  feet,  a 
slope  of  .00017  or  about  n  inches  per  mile  produces  a  velocity  of 
2.86  feet  per  second,  with  discharge  of  1407  second-feet.  This 
velocity  is  best  suited  to  the  light  soil  in  which  the  canal  is  ex- 
cavated. Further  along  for  diminished  discharge  and  bed- 
width  of  25  feet,  the  same  depth  and  slope  being  maintained,  the 
velocity  is  as  high  as  2.78  feet  without  doing  damage. 

153.  Cross-sections. — The  most  economical  channel  is  one 
with  vertical  sides  and  a  depth  equal  to  half  the  bottom  width; 
but  this  form  is  only  applicable  to  the  firmest  rock,  therefore 
trapezoidal  cross-sections  are  always  employed  in  other  materials. 
The  best  trapezoidal  form  is  one  in  which  the  width  of  the  water 
surface  is  double  the  bottom  width  and  equal  to  the  sum  of  the 
side  slopes,  and  the  trapezoidal  section  which  gives  the  maximum 
discharge  for  any  area  of  waterway  is  semi-hexagonal,  or  one  in 
which  the  hydraulic  mean  depth  equals  half  the  depth  of  water. 
Such  cross-sections  as  these,  however,  would  call  for  an  unusually 
compact  material.  In  the  interest  of  economy  the  side-slopes 
above  water-level  should  be  as  steep  as  the  nature  of  the  soil  will 
permit.  As  before  shown,  the  cross-sectional  area  depends  on  the 
velocity  and  slope  and  their  relation  to  the  quantity  of  water  to 
be  discharged.  The  exact  form  of  this  cross-section  is  dependent 
on  the  topography  and  the  material  through  which  the  canal 
passes.  The  greater  the  depth  the  greater  will  be  the  velocity 
and  consequent  discharge  for  the  same  form  of  cross-section. 

Very  large  canals,  such  as  some  of  those  in  India,  have  been 
given  a  proportion  of  depth  to  width  similar  to  that  of  the  great 
rivers.  This  proportion  has  been  found  to  be  most  nearly  attained 
when  the  bed  width  is  made  from  13  to  16  times  the  depth.  In 
sidehill  excavation  the  greater  the  proportion  of  depth  to  width 
the  less  will  be  the  cost  of  construction  (Art.  143),  and  in  all  rock 
and  heavy  material  it  is  desirable  if  possible  to  make  the  bottom 
width  not  greater  than  from  2  to  3  times  the  depth.  Such  a  pro- 
portion as  this,  however,  is  rarely  practicable.  In  a  large  canal, 


152  ALIGNMENT,     SLOPE,     AND    CROSS-SECTION 

one  for  instance  having  a  capacity  of  2000  second-feet,  with  a 
velocity  of  2  feet  per  second,  the  cross-sectional  area  would  be 
1000  square  feet.  If  the  proportion  of  2  to  i  were  maintained, 
this  would  call  for  a  bed  width  of  about  45  feet  to  a  depth  of  22 J 
feet.  Such  a  depth  as  this,  unless  in  very  hard  material,  is  readily 
seen  to  be  absurd,  as  the  cost  of  construction  would  be  greatly 
increased  over  that  of  a  canal  having  a  lesser  depth.  In  this  case 
a  fair  proportion  would  be  125  feet  bed  width  to  about  8  feet 
depth.  A  rule  which  has  been  proposed,  and  which  will  prove 
fairly  good  on  moderate  sized  canals,  is  to  make  the  bottom 
width  in  feet  equal  to  the  depth  in  feet  plus  one,  squared.  This, 
however,  will  not  apply  to  large  canals  and  is  not  altogether  true 
for  any  size  of  canal. 

154.  Form  of  Cross-section. — The  cross-section  of  a  canal 
may  be  so  designed  that  the  water  may  be  wholly  in  excavation, 
wholly  in  embankment,  or  partly  in  excavation  and  partly  in 
embankment  (Fig.  19).  The  conditions  which  govern  the  choice 
of  one  of  these  three  forms  are  dependent  primarily  on  the  align- 
ment and  grade  of  the  canal,  and  secondarily  on  the  character  of 
the  soil.  For  sanitary  reasons  it  is  sometimes  desirable  to  keep  a 
canal  wholly  in  cutting,  for  if  the  material  of  which  the  banks 
are  constructed  is  porous  the  water  may  filter  through  and  stand 
about  in  stagnant  pools  on  the  surface  of  the  ground.  If  the 
material  is  impervious  to  the  passage  of  water  and  will  form  good 
firm  banks,  it  may  be  well  to  keep  the  canal  in  embankment 
where  possible,  though  this  may  necessitate  the  expense  of  bor- 
rowing material.  In  order  to  lessen  the  cost  of  construction,  it  is 
desirable,  where  the  surface  will  permit,  to  keep  a  canal  half  in 
cut  and  half  in  fill,  thus  reducing  to  a  minimum  the  amount  of 
material  to  be  moved.  Ordinarily  the  surface  of  the  ground  is 
irregular  and  undulating,  and  in  order  that  the  grade  may  be 
maintained  the  canal  will  of  necessity  be  sometimes  wholly  in 
cut  and  at  others  wholly  in  fill,  and  at  others  at  all  intermediate 
stages  between  these.  Where  the  canal  is  wholly  in  embankment 
there  is  always  considerable  loss  from  leakage,  and  consequent 
danger  of  breaches.  Where  the  canal  is  wholly  in  cut,  care  must 
be  taken  to  discover  the  character  of  the  soil  in  which  the  excava- 


FORM     OF    CROSS-SECTION 


153 


tion  is  to  be  made,  as  rock  may  be  encountered  at  a  few  inches 
below  the  surface,  thus  increasing  the  cost  of  excavation,  or  a 
sandy  substratum  may  be  discovered  which  would  cause  exces- 
sive seepage. 

Most  main  canals  follow  the  slope  of  the  country  on  grade 
contours  running  around  sidehill  or  mountain  slopes.  In  such 
cases  it  is  necessary  to  build  an  embankment  on  one  side  only, 
when  the  cutting  will  be  entirely  on  the  upper  side.  If  there  is  a 
gentle  slope  on  the  upper  side,  and  an  embankment  on  that  side, 

SIDELONG  GROUND  W.L  ABOVE  C.L. 

4V 

W.L.      «£ 


Majr  require  Puddle  Wall 
as  indicated 


SOD  REVETMENTS 


WITHOUT  BERMS- W.L  BELOW  C.L, 


Ground 


WITH  BERMS- W.L.  BELOW  C.L 


FIG.  19. — Various  Canal  Cross-sections. 

it  is  desirable  to  run  drainage  channels  at  intervals  from  this 
embankment  to  keep  the  water  from  making  its  way  through  it 
to  the  canal.  These  drainage  channels  may  be  taken  through 
the  embankment  into  the  canal,  or  may  be  led  away  to  some 
natural  watercourse. 

In  designing  the  cross-section  of  a  canal  it  may  be  desirable 
to  give  a  berm,  and  this  may  be  above  or  below  the  water-level 
(Fig.  19).  Ordinarily  the  berm  is  left  at  a  level  with  the  ground 
surface,  though  it  may  be  constructed  in  excavation  or  embank- 
ment— an  unusual  practice,  however.  The  chief  object  of  the 
berm  is  to  provide  against  the  destruction  of  the  slopes  in  the 
lower  part  of  the  banks  by  giving  a  terrace  or  bench  on  which  the 


154  ALIGNMENT,     SLOPE,     AND    CROSS-SECTION 

upper  bank  may  slide,  provided  it  fails  to  maintain  the  slope 
originally  given ;  it  also  serves  in  some  cases  as  a  tow-path  or  foot- 
path. The  width  of  berm  varies  between  2  and  6  feet,  and  it  is 
common  to  change  the  slopes  at  the  point  of  junction  between 
cut  and  embankment,  making  the  slope  of  the  latter  a  little  flatter 
than  that  of  the  former. 

155.  Side  Slopes  and  Top  Width  of  Banks. — In  large  canals 
it  is  always  desirable  to  have  a  roadbed  on  at  least  one  bank,  and 
the  width  of  this  will  determine  the  top  width  of  the  bank.  The 
inner  surfaces  of  the  canal  are  usually  made  smooth  and  even, 
while  the  top  is  likewise  made  smooth,  with  a  slight  inclination 
to  the  outward  to  throw  drainage  away  from  the  canal.  The 
inner  slopes  of  the  banks  vary  in  soil  between  i  on  i  and  i  on  4, 
according  to  the  character  of  the  material.  In  firm  clayey 
gravel  or  hardpan  slopes  of  i  on  i  are  sufficiently  substantial  for 
nearly  any  depth  of  cutting  or  embankment.  On  the  Turlock 
canal  in  California  is  a  cut  80  feet  in  depth  with  side  slopes  of 
i  on  i,  while  on  the  Bear  River  canal  in  Utah  are  similar  slopes 
in  disintegrated  shale  and  coarse  gravel.  In  ordinary  firm  soil 
mixed  with  gravel  or  in  coarse  loamy  gravel  slopes  of  i  on  i  J  are 
sufficient.  In  firm  soil  and  slightly  clayey  loam  slopes  of  i  on  2 
may  be  required;  on  lighter  soils  these  slopes  may  be  increased 
until  the  lightest  sand  is  reached,  when  slopes  of  i  on  3  or  4  may 
be  necessary. 

The  top  width  of  the  canal  bank  is  generally  from  4  to  10 
feet,  according  to  the  material  and  depth,  and  whether  or  not  the 
water  is  in  embankment.  If  there  is  to  be  no  roadway  on  the  top 
of  the  embankment,  and  the  surface  of  the  water  does  not  rise 
more  than  a  foot  or  so  above  the  foot  of  the  embankment,  a  top 
width  of  4  feet  is  sufficient.  Where  the  depth  of  water  on  the 
embankment  is  greater,  this  width  should  be  6  or  8  feet,  and  if 
the  soil  is  light  it  should  be  at  least  10  f  eet.  It  is  sometimes  neces- 
sary to  build  a  puddle  wall  in  the  embankment,  or  to  make  a 
puddle  facing  on  its  inner  slope  where  is  it  particularly  pervious 
to  water.  The  same  effect  is  obtained  by  sodding  or  causing 
grass  to  grow  on  the  bank.  It  may  be  well  to  puddle  the  entire 
bank  during  construction  by  laying  and  rolling  it  in  layers.  The 


CROSS-SECTION    WITH    SUBGRADE  155 

carrying  capacity  of  a  canal  should  be  so  calculated  that  the  sur- 
face of  the  water  when  in  cut  shall  not  reach  within  one  foot  of 
the  top  of  the  ground  surface.  In  fill  the  depth  of  water  carried 
should  be  such  that  the  surface  shall  not  rise  higher  than  within 
ij  feet  of  the  top  of  the  bank,  while  if  the  fill  is  great  it  is  often 
unsafe  to  let  the  water  rise  within  2  feet  of  the  top  of  the  bank. 

156.  Cross-section  with  Subgrade. — In  the  light  soils  of  the 
San  Luis  valley  in  Colorado  and  in  Kern  valley  in  California 


FIG.  20. — Cross-section  of  Galloway  Canal  in  Sand,  showing  Subgrade. 

it  has  been  found  advantageous  to  dig  a  subgrade  i  to  2  feet  below 
the  original  canal  bed.  The  cross-section  gradually  approaches 
that  of  the  ellipse  and  tends  to  keep  the  current  in  the  centre  of 
the  channel,'  and  to  keep  up  its  flow  with  the  least  exposure  to 
friction  and  seepage  when  the  volume  of  water  in  the  canal  is  low. 
The  subgrade  (Fig.  20)  is  given  by  practically  designing  the  canal 
as  if  it  were  to  have  a  trapezoidal  cross-section  with  berm,  and 


FIG.  21. — Typical  Section  of  Lined  Canal.     Reclamation  Service. 

then  evening  off  the  slope  by  removing  the  berm  and  continuing 
the  slope  from  the  bottom  of  the  canal  toward  the  centre.  In 
such  construction  as  this  it  has  sometimes  been  found  desirable 
to  give  the  bank  practically  no  top  width,  simply  rounding  it  off 
from  the  innner  to  the  outer  surface,  where  the  waste  is  carelessly 
scattered,  allowing  the  soil  to  assume  its  natural  slope. 

157.  Lined  Canal. — There  are  many  advantages  to  be  gotten 
from  lining  a  canal  channel  excavated  in  earth,  especially  where 


156  ALIGNMENT,     SLOPE,     AND     CROSS-SECTION 

the  soil  is  porous  and  water  valuable.  In  many  portions  of  India 
and  in  Europe,  particularly  where  the  canal  passes  through  sandy 
soil,  or  where  a  high  velocity  is  desirable  or  unavoidable, 
the  canals  are  lined  for  portions  of  their  lengths,  usually  with 
sand  placed,  dry-laid  stone  paving.  In  some  portions  of  South- 
ern California  canals  are  similarly  lined,  though  there,  owing 
to  the  high  value  of  water,  it  is  customary  to  line  them  with 
rubble  paving  set  in  cement  or  mortar  in  order  to  prevent  loss 
by  absorption.  The  Reclamation  Service  has  lined  portions  of 
many  of  its  canals  with  concrete,  particularly  those  in  the 
Southwest  where  water  is  scarce  and  valuable.  Such  linings  have 


FIG,  22. — Cross -section  of  Lined  Channel,  Santa  Ana  Canal. 

been  used  chiefly  in  sandy  sections  and  through  crevised  rock 
sections,  the  concrete  being  generally  6  inches  in  thickness. 
When  a  canal  is  thus  lined  its  cost  is  in  the  end  not  greatly  in- 
creased, for  the  saving  in  cross-sectional  area  due  to  the  ability  to 
increase  the  velocity,  as  well  as  the  great  saving  of  water  in  sandy 
and  gravelly  soils,  largely  offsets  the  cost  of  lining;  moreover,  it 
is  possible  to  give  a  lined  channel  a  cross-section  more  nearly 
approaching  that  called  for  by  theory  (Art.  153),  namely,  a  greater 
relative  depth  to  width,  because  of  the  stability  added  to  the  banks 
by  the  lining. 

Experiments  conducted  by  B.  A.  Echeverry  in  Southern 
California  to  determine  relative  percolation  from  lined  and  un- 
lined  ditches  showed  the  following  relative  efficiency  ratios.  Using 
unlined  earth  channels  £  =  i.o;  heavy  oil  lining,  3^  gals,  per  sq. 
yd.,e  =  2.o;  clay  puddle,  e  =  1.8;  cement  concrete  3"  thick,  e  =  7. 2. 


LINED   CANAL 


157 


The  cost  of  the  oil  lining  was  n  cents  per  sq.  yd;  of  the  concrete 
lining  67  cents. 

A  typical  paved  lining  is  that  given  the  Santa  Ana  canal  in 
California,   in   alluvial   soil,   sand,   and  gravel.     This   canal   is 


FIG.  23.— Concrete  Lining,  Truckee-Carson  Canal,  Nevada. 

almost  wholly  in  excavation  (Plate  III) ;  the  water  is  permitted  a 
velocity  of  5  feet  per  second,  and  the  depth  is  as  great  as  7^  feet 
for  a  bed  width  of  6J  feet  and  top  width  of  12 J  feet  (Fig.  22).  In 
order  that  the  lining  may  have  a  stable  footing  and  the  bottom 


158  ALIGNMENT,    SLOPE,    AND    CROSS-SECTION 

be  less  liable  to  bulge,  this  is  curved  downward  with  a  versed  sine 
of  ij  feet,  forming  thus  a  subgrade  of  that  depth.  The  banks 
are  2  feet  higher  than  the  water  surface,  and  are  built  on  side 
slopes  of  2  on  i.  The  earth  excavation  had  a  bottom  width  of  7 
feet  and  the  same  slopes  as  above,  and  was  trimmed  at  bottom  to 
the  lining,  which  consists  of  cobbles  and  bowlders  laid  in  mortar 
and  grouted  and  faced  with  cement  plaster. 

On  the  Tieton  canal,  Washington,  of  the  Reclamation  Service, 
the  lined  sections  in  earth  and  loose  rock  are  semicircular 
(Fig.  23).  The  lining  is  of  reinforced  concrete,  4  inches  in 


1 

1 

4-4|:     ( 

L 

\L|j$»3Iortar 

Joine 

',  1 

^Jute 

* 

;v 

DETAIL  OF  JOINT 
i  Square, 


r—      —  6'2— 
FIG.  24. — Reinforced  Concrete  Canal  Lining.     Tieton  Canal,  Wash. 

thickness,  and  extends  i'  10"  above  the  centre  of  the  circular 
section.  The  upper  edge  is  cross-braced  every  2  feet  by  a  4-inch 
square  scantling.  The  diameter  of  the  lined  section  is  8'  2",  depth 
of  water  5'  3",  area  36  square  feet,  velocity  9  feet  per  second, 
and  discharge  326  second-feet.  By  comparison  the  unlined 
section  of  the  same  canal  has  an  area  of  120  square  feet  and 
velocity  of  2.5  feet  per  second. 

Below  the  Assuan  dam  in  upper  Egypt  is  a  canal  built  in 
shifting  sand  by  erecting  on  the  surface  a  semicylindrical  flume 
of  sheet  steel  and  then  banking  the  sand  against  it  to  the  level  of 
its  top.  This  steel  canal  is  19'  8"  in  diameter  with  i'  8"  straight 


SHRINKAGE    OF    EARTHWORK 


159 


sides  at  top,  making  a  total  depth  of  21'  4".  The  inner  shell  of 
\"  steel  plates  is  riveted  to  outer  semicircular  ribs  of  heavy  T-rail 
placed  2 y  centres.  The  top  is  braced  with  3"  flat  and  3"  x  2  y 
angle  iron  (Fig.  25).  The  canal  rests  on  a  wall  of  concrete 
beneath  its  centre  and  has  expansion  joints  every  330  feet. 

158.  Shrinkage  of  Earthwork. — It  is  well  known  that  when 


Wro't  Steel  Rails  2  3  Ion* 

Angle  In  5  lengths  on 

Atmospheric  aide 

jointmarned''6" 


CROSS  SECTION  ON  LINE  A-B 
FIG.  25. — Plan  and  Section,  Sheet  Steel  Flume,  Upper  Egypt. 

soil  which  has  been  removed  from  an  excavation  is  formed  into 
embankment  it  settles  or  shrinks  in  volume.  That  is  to  say,  the 
embankment  soil  occupies  a  less  space  than  it  did  in  the  ground; 
while,  on  the  contrary,  rock  or  loose  stone  occupies  a  greater 
space,  depending  on  the  dimensions  of  the  fragments.  The 
percentage  of  this  shrinkage  differs  for  different  soils.  The 


i6o 


ALIGNMENT,    SLOPE,    AND   CROSS-SECTION 


following  list  gives  an  idea  of  the  amount  of  this  shrinkage  for 
different  soils: 

Sand,  about  10  per  cent;  in  other  words,  after  excavation  sand 
will  ultimately  occupy  10  per  cent  less  space  than  it  did  in  its 
natural  bed. 

Sand  and  gravel  shrink  8  per  cent. 

Earth,  loam,  and  sandy  loam  shrink  10  to  12  per  cent. 

Gravelly  clay  shrinks  8  to  10  per  cent. 

Puddled  clay  and  puddled  soil  shrink  20  to  25  per  cent. 


FIG.  26. — Rock  Cross-section,  Turlock  Canal. 

Rock  expands  or  increases  in  volume  from  25  per  cent  in  the 
case  of  small  or  medium  fragments  and  road -met  ailing  to  60  or 
70  per  cent  in  large  fragments  carelessly  thrown. 

159.  Cross-section  in  Rock. — In  firm  rock  it   is  desirable 


ry'Rubble 


SECTION  IN  ROCK 
a  =87.7        p=15.4  r=  2.44 

w=.oi2      s=.oom 

Q=300 

B 


FlG.  27. — Rock  Cross-section;  A,  Bear  River  Cana.;  B,  Umatilla  Canal. 


CROSS-SECTION   IN    ROCK 


161 


SECTION  "A-A" 


R«|,G  Think 


to  make  the  proportion  of  depth  to  width  about  as  i  to  2,  with  side 
slopes  of  about  4  on  i.  In  less  firm  rock  lighter  slopes  and  a  less 
proportional  depth  are  desirable.  In  friable  shale,  as  on  the  Tur- 
lock  canal  in  California,  a  different  cross-section  is  desirable 
(Fig.  26).  In  this  instance  a  retaining- wall  of  hand-placed  stones, 
with  an  outer  slope  of  4  on  i  and  a  top  width  of  2  J  feet,  is  built  on 
the  lower  side.  Inside  this  is  a  puddled  earth  bank,  riprapped  on 
the  water  surface  with  10  inches  in 
thickness  of  loose  stone.  The  upper 
or  excavated  slope  is  about  2  on  i, 
the  depth  10  feet,  and  the  bed  width 
20  feet.  The  slopes  have  proven  too 
steep,  as  the  friable  shale  has  disin- 
tegrated and  caused  the  made  banks 
and  the  sides  of  excavated  banks  to 
crumble  and  fall.  On  the  Bear 
River  canal  in  Utah,  and  the 
Umatilla  canal,  Oregon,  the  cross- 
sections  shown  in  Fig.  27,  were 
given  in  order  to  avoid  too  much  ex- 
cavation in  extremely  rocky  sidehill, 
a  retaining-wall  being  built  as  the 
lower  or  embankment  wall  of  the 
canal. 

The  transition  from  rock  to  earth 
must  be  made  with  great  care  lest 
erosion  take  place  in  the  latter.  For 
the  same  volume  of  discharge  the 
earth  section  usually  has  greater 
breadth,  less  depth  and  diminished 
slope  to  reduce  the  velocity.  As  a 
rule  the  canal  bottom  and  sides  are  riprapped  where  the  change 
in  section  occurs,  as  illustrated  (Fig.  28)  on  the  Umatilla  canal, 
Oregon,  of  the  Reclamation  Service. 


Conoreto 
6'thlok 


FIG.  28.  —  Transition  from 
Rock  to  Earth  Cross-section, 
Lined  Canal,  Reclamation  Ser- 
vice. 


IT 


CHAPTER  X 

HEADWORKS    AND    DIVERSION    WEIRS 

1 60.  Location  of  Headworks. — The  head  works  of  a  canal 
are  generally  placed  where  the  stream  emerges  from  the  hills. 
At  such  a  point  the  slope  of  the  country  and  of  the  stream  is  steep, 
making  it  possible  to  conduct  a  canal  thence  to  the  irrigable  lands 
with  the  shortest  diversion  line.  Moreover,  the  width  of  the  chan- 
nel of  the  stream  is  generally  contracted,  and  it  flows  through 
firm  soil  or  rock,  thus  permitting  a  reduction  in  the  length  of  the 
weir  and  in  the  cost  of  its  construction  and  maintenance.  As 
one  of  the  principal  objects  of  the  diversion  weir  is  to  raise  the 
level  of  the  water  and  force  it  into  the  canal  head,  one  of  the  con- 
trolling factors  in  determining  the  site  of  the  headworks  is  the 
height  of  the  weir.  This  again  is  dependent  on  the  effect  of  vari- 
ous weir  heights  on  the  location  and  cost  of  the  remainder  of  the 
headworks  and  of  the  diversion  canal.  Also  on  the  flood  dis- 
charges, amounts  of  sediment  carried  by  the  stream,  the  founda- 
tion, the  depth  of  water  in  the  canal,  and  similar  factors. 

When  the  volume  of  flood  water  occurring  in  the  stream  is 
great  it  is  sometimes  necessary  to  locate  the  headworks  at  a  point 
where  the  width  between  banks  is  greatest,  in  order  that  the  depth 
of  water  flowing  over  the  weir  may  be  reduced  to  a  minimum  and 
danger  of  its  destruction  reduced  accordingly.  While  such  a 
location  may  be  the  most  permanent,  it  is  also  most  costly  for  con- 
struction. The  site  of  the  headworks  should  be  such  that  the 
most  permanent  weir  can  be  constructed  at  the  least  cost,  and  yet 
they  should  be  so  located  that  the  diverting  canal  can  be  conducted 
thence  to  the  irrigable  lands  at  a  minimum  cost.  The  location 
of  the  headworks  high  up  on  the  stream  is  usually  antagonistic  to 
the  last  object,  since  it  generally  results  in  the  canal  having  to 
encounter  heavy  rock-work  and  difficult  construction  until  it  gets 
away  from  the  river  banks.  In  selecting  the  site  for  the  head- 

162 


CHARACTER   OF   HEADWORKS  163 

works  it  is  desirable  to  choose  a  portion  of  the  stream  in  which  its 
channel  is  straight  and  its  cross-section  uniform  for  some  distance. 
If  the  site  is  in  a  wide  portion  of  the  stream,  the  weir  should  be 
located  at  a  point  where  the  stream  shows  no  signs  of  shifting  its 
channel. 

161.  Character  of  Headworks. — The  headworks  of  a  canal 
consist  of— 

1.  A  diversion  weir,  in  which  is  usually  built 

2.  A  set  of  scouring  sluices; 

3.  A  regulator  at  the  head  of  the  canal  for  its  control; 

4.  A  wasteway  for  the  relief  of  the  canal  below  that  point. 
Sometimes  to  these  are  added  river  training  or  regulating  works 

for  the  protection  of  the  banks  of  the  stream  above  and  below  the 
obstruction  formed  by  the  headworks.  Too  careful  attention 
cannot  be  given  to  an  examination  of  the  stream  at  the  point  of 
diversion.  Soundings  and  borings  should  be  made  to  ascertain 
the  depth  of  water  and  character  of  the  foundation.  The  velocity 
of  the  stream  and  its  flood  heights  should  be  studied,  as  should 
the  material  of  which  the  banks  are  composed.  Where  possible, 
a  straight  reach  in  the  river  should  be  chosen  for  the  location  of 
the  headworks  in  order  that  the  stream  shall  have  a  direct  sweep 
past  them,  thus  reducing  to  a  minimum  the  deposition  of  silt  in 
front  of  the  regulating  gates.  If  possible,  a  point  should  also  be 
chosen  where  the  velocity  in  the  river  will  not  exceed  that  in  the 
canal,  so  that  the  deposition  of  silt  shall  be  further  reduced. 

There  has  been  too  great  a  tendency  in  American  construc- 
tion to  build  works  of  a  temporary  and  transient  character.  The 
headworks  of  a  canal  are  the  most  vital  portions  of  its  mechanism ; 
they  are  to  a  canal  system  what  a  throttle-valve  is  to  a  locomotive. 
Through  them  the  permanency  of  the  supply  in  the  canal  is  main- 
tained, and  any  injury  to  them  means  paralysis  to  the  entire  sys- 
tem. They  should  therefore  be  most  substantially  and  carefully 
designed  throughout.  The  employment  of  wood  has  been  alto- 
gether too  common  in  the  United  States.  It  is  very  well  to  make 
use  of  wood  as  a  temporary  makeshift  until  money  and  time  can 
be  found  for  substituting  more  substantial  material.  It  may  be 
generally  laid  down  as  a  principle,  however,  that  only  iron  and 


164  HEADWORKS    AND    DIVERSION    WEIRS 

masonry  should  enter  into  the  construction  of  the  head  works.  It 
is  impossible  to  form  wood,  with  the  addition  of  little  or  no  iron 
or  masonry,  into  permanent  and  substantial  headworks.  Until 
recently  the  best  and  most  abundant  examples  of  substantial 
headworks  were  to  be  found  in  Europe  and  India.  Now  the 
works  of  the  Reclamation  Service  furnish  magnificent  examples 
of  modern  reinforced  concrete  construction. 

In  some  cases  it  has  been  found  unnecessary  to  construct 
diversion  weirs  as  a  part  of  the  headworks  of  a  canal.  This  has 
been  the  case  especially  where  the  discharge  of  the  stream  was 
great  relative  to  the  discharge  of  the  canal,  and  only  when  a  por- 
tion of  the  water  in  the  stream  was  required.  At  the  head  of  the 
Ganges  and  Jumna  canals  in  India  there  are  no  permanent  diver- 
sion works,  the  water  being  turned  into  the  canal  head  by  means 
of  temporary  structures  of  bowlders,  or  by  means  of  training  the 
water  of  the  river  so  that  it  shall  flow  directly  against  the  canal 
head. 

162.  Diversion  Weirs. — In  this  book  the  word  weir  as  dis- 
tinguished from  dam  is  generally  employed  to  mean  a  structure 
intended  for  the  impounding  or  the  diversion  of  water  and  over 
which  flood  waters  may  safely  flow.  Thus  weirs  are  usually  built 
at  the  heads  of  canals  for  the  diversion  of  the  waters  of  the  stream 
into  their  heads,  while  the  surplus  water  is  permitted  to  flow  over 
the  weir  and  to  pass  on  down  the  stream.  In  some  cases,  however, 
dams  over  which  it  would  be  unsafe  to  permit  flood  waters  to  pass 
are  used  for  the  purpose  of  diversion,  and  a  wasteway  is. con- 
structed at  one  end  of  the  dam  for  the  passage  of  surplus  waters. 

A  weir  across  a  stream  is  analogous  to  a  bar  and  should  be 
located  and  treated  as  such.  If  it  is  placed  at  the  widest  part  of 
the  stream,  the  cost  of  construction  may  be  increased.  In  the 
great  rivers  of  India  and  on  the  Colorado  River  at  Yuma  where 
diversion  is  made  in  the  level  and  sandy  plains  below  the  hills  and 
where  permanent  foundations  cannot  be  obtained,  weirs  have 
generally  been  placed  in  the  broadest  reaches  of  the  streams. 
(PL  V.)  In  our  own  country  diversion  for  canals  has  generally 
taken  place  in  the  foothills,  and  accordingly  the  narrower  portions 
of  the  streams  have  been  chosen  for  this  purpose. 


CLASSES    OF   WEIRS  165 

The  integrity  of  weirs  is  in  constant  danger  of  destruction: 
i,  by  actual  breaching  by  the  force  of  the  current;  2,  by  under- 
mining by  the  falling  water;  3,  by  outflanking,  especially  where 
the  banks  are  unstable  or  not  protected  by  substantial  wing-walh; 
4,  by  undermining  on  the  upper  side  by  parallel  currents  owing 
to  the  weir  not  being  at  right  angles  to  the  course  of  the  stream. 
This  may  be  remedied  by  the  building  of  suitable  training  works 
(Art.  191). 

163.  Classes    of    Weirs. — Weirs    may    be    divided    into    two 
classes   according  to  the  mode  of   building  their  foundations. 
Thus  they  may  rest  directly  on  some  permanent  material;  or  they 
may  rest  on  some  unstable  material,  as  quicksand,  gravel,  or  clay, 
in  which  case  an  artificial  foundation  of  piles,  caissons,  or  wells  or 
blocks  must  be  constructed.     Where,  in  Western  practice,  a  firm 
foundation  has  not  been  found  piling  has  usually  been  employed. 
In  India  and  Egypt  wells  or  blocks  are  employed  for  foundations 
in  unstable  material. 

Foundations  of  the  first  class,  viz.,  in  rock  or  bowlders,  are 
found  in  the  foothills  and  at  canyon  exits,  and  where  the  slope  of 
the  stream-bed  exceeds  8  feet  per  mile.  Those  of  the  second  class 
are  found  in  valleys  and  on  the  plains  where  the  stream-bed  has 
slopes  less  than  8  feet  per  mile. 

The  most  convenient  classification  of  diversion  weirs  is  accord- 
ing to  the  construction  of  their  superstructures.  These  may  be— 

1.  Temporary  brush  or  bowlder  barriers; 

2.  Rectangular  walls  of  sheet  and  anchor  piles  filled  with  rock 
or  sand; 

3.  Open  weirs; 

4.  Wooden  crib  and  rock  weirs; 

5.  Masonry  weirs; 

164.  Brush  and  Bowlder  Weirs. — The  simplest  and  crudest 
form  of  weir  is  the  brush  and  gravel  barrier,  which  was  originally 
used  by  the  Mexicans  and  is  still  employed  in  the  West  on  minor 
streams.     These  weirs  are  formed  by  driving  stakes  across  the 
channel  and  attaching  to  them  fascines  or  bundles  of  willows  from 
three  to  six  inches  in  diameter  at  the  butts,  which  are  laid  with 
the  brush  end  up-stream,  and  are  weighted  with  bowlders  and 


1 66  HE  AD  WORKS    AND    DIVERSION    WEIRS 

gravel.  More  willow  or  cottonwood  branches  are  laid  on  the 
top  of  these  and  again  weighted  with  bowlders,  this  operation 
being  continued  until  the  structure  is  built  to  a  height  of  three  or 
four  feet.  Such  structures  are  of  the  crudest  character,  can  be 
built  without  any  engineering  knowledge  or  supervision,  and  are 
carried  away  by  the  first  flood. 

165.  Rectangular  Pile  Weirs. — These  have  been   employed 
in  wide  sandy  rivers  like  the  Platte,  in  Colorado.     They  consist 
of  a  double  row  of  piling  driven  into  the  river-bed,  the  two  rows 
being  about  6  feet  apart,  and  the  piles  about  3  feet  apart  between 
centres.     Between  these  is  driven  sheet  piling  to  prevent  the  seep- 
age or  travel  of  water  through  the  barrier,  and  the  upper  portion 
of  the  structure  is  planked  so  as  to  form  a  rectangular  wall  the 
interior  of  which  is  filled  in  with  gravel,  sand,  etc.     Such  walls  are 
usually  low,  rarely  exceeding  8  feet  in  height,  and  after  the  upper 
side  is  backed  with  the  silt  deposited  from  the  stream  they  form 
substantial  barriers  which  may  last  a  few  years.     Such  struc- 
tures cannot  be  employed  where  the  flood  height  is  great,  as  they 
would  soon  be  undermined  unless  substantial  aprons  were  con- 
structed. 

1 66.  Open  and  Closed  Weirs. — Diversion  weirs  may   again 
be  classified  as  open  or  closed.     A  closed  weir  is  one  in  which 
the  barrier  which  it  forms  is  solid  across  nearly  the  entire  width 
of  the  channel,  the  flood  waters  passing  over  its  crest.     Such 
weirs  have  usually  a  short  open  portion  in  front  of  the  regulator 
known  as  the  "scouring-sluice,"  the  object  of  which  is  to  main- 
tain a  swift  current  past  the  regulator  entrance,  and  thus  prevent 
the  deposit  of  silt  at  that  point.     An  open  weir  is  one  in  which 
scouring-sluices  or  openings  are  provided  throughout  a  large  por- 
tion of  its  length  and  for  the  full  height  of  the  weir. 

The  advantage  of  the  closed  weir  is  that  it  is  self-acting,  and 
if  well  designed  and  constructed  requires  little  expense  for  repairs 
or  maintenance.  It  is  a  substantial  structure,  well  able  to  with- 
stand the  shocks  of  floating  timber  and  drift;  but  it  interferes 
with  the  normal  regimen  of  the  river,  causing  deposit  of  silt  and 
perhaps  changing  the  channel  of  the  stream.  Open  or  scouring- 
sluice  weirs  interfere  little  with  the  normal  action  of  the  stream, 


OPEN    AND   CLOSED   WEIRS  167 

and  the  scour  produced  by  opening  the  gates  prevents  the  deposit 
of  silt,  while  their  first  cost  is  generally  less  than  that  of  closed 
weirs 

The  closed  weir  consists  of  an  apron  properly  founded  and 
carried  across  the  entire  width  of  the  river  flush  with  the  level  of 
its  bed,  and  protected  from  erosive  action  by  curtain-walls  up 
and  down  stream.  On  a  portion  of  this  is  constructed  the  super- 
structure, which  may  consist  of  a  solid  wall  or  in  part  of  upright 
piers,  the  interstices  between  which  are  closed  by  some  temporary 
arrangement.  This  portion  of  the  weir  is  called  the  scouring- 
sluice.  The  apron  of  the  weir  should  have  a  thickness  equal  to 
one-half  and  a  breadth  equal  to  three  times  the  height  of  the  weir 
above  the  stream-bed.  During  floods  the  water  backed  against 
the  weir  acts  as  a  water  cushion  to  protect  the  apron,  and  as  the 
flood  rises  the  height  of  the  fall  over  the  weir  crest  diminishes,  so 
that  with  a  flood  of  16  feet  over  an  ordinary  weir  its  effect  as  an 
obstruction  wholly  disappears.  A  rapidly  rising  flood  is  more 
dangerous  than  a  slowly  rising  flood,  not  only  because  of  its  greater 
velocity,  but  because  it  causes  a  greater  head  or  fall  over  the  weir 
as  the  water  has  not  had  time  to  back  up  below  and  form  a  water- 
cushion.  For  the  same  reasons  a  falling  or  diminishing  flood  is 
less  dangerous  than  a  rising  flood. 

An  open  weir  consists  of  a  series  of  piers  of  wood,  iron,  or 
masonry,  set  at  regular  intervals  across  the  stream  bed  and  rest- 
ing on  a  masonry  or  wooden  floor.  This  floor  is  carried  across 
the  channel  flush  with  the  river  bed,  and  is  protected  from  erosive 
action  by  curtain-walls  up-  and  down-stream.  The  piers  are 
grooved  for  the  reception  of  flashboards  or  gates,  so  that  by  rais- 
ing or  lowering  these  the  afflux  height  of  the  river  can  be  con- 
trolled. The  distance  between  the  piers  varies  between  3  and  10 
feet,  according  to  the  style  of  gate  used.  If  the  river  is  subject 
to  sudden  floods  these  gates  may  be  so  constructed  as  to  drop 
automatically  when  the  water  rises  to  a  sufficient  height  to  top 
them.  It  is  sometimes  necessary  to  construct  open  weirs  in  such 
manner  that  they  shall  offer  the  least  obstruction  to  the  waterway 
of  the  stream.  This  is  necessary  in  weirs  like  the  Barage  du  Nil, 
below  Cairo,  Egypt,  or  in  some  of  the  weirs  on  the  Seine,  in  France, 


1 68  HEADWORKS   AND   DIVERSION    WEIRS 

in  order  that  in  time  of  flood  the  height  of  water  may  not  be  appre- 
ciably increased  above  the  fixed  diversion  height.  Should  the 
height  be  increased  in  such  cases  the  water  would  back  up,  flood- 
ing and  destroying  valuable  property  in  the  cities  above.  Under 
such  circumstances  open  weirs  are  sometimes  so  constructed  that 
they  can  be  entirely  removed,  piers  and  all,  leaving  absolutely  no 
obstruction  to  the  channel  of  the  stream,  and  in  fact  increasing 
its  discharging  capacity,  owing  to  the  smoothness  which  they 
give  to  its  bed  and  banks. 

167.  Open  Frame  or  Flashboard  Weirs. — A  form  of  cheap 
open  weir  which  has  been  commonly  constructed  in  the  West  is 
the  open  wooden  frame  and  flashboard  weir.  This  type  of  struc- 
ture is  used  only  on  such  rivers  as  have  unstable  beds  and  banks, 
where  any  obstruction  to  the  ordinary  regimen  of  the  stream 
would  cause  a  change  in  its  channel.  It  consists  wholly  or  in 
part  of  a  foundation  of  piling  driven  into  the  river  bed,  upon 
which  is  built  an  open  framework  closed  by  horizontal  planks  let 
into  slots  in  the  piers.  These  weirs  are  constructed  of  wood,  and 
are  temporary  in  character,  their  chief  recommendation  being 
the  cheapness  with  which  they  can  be  built  in  rivers  the  beds  of 
which  are  composed  of  a  considerable  depth  of  silt  or  light  soil. 

Two  varieties  of  this  weir  are  in  common  use.  One  which  has 
been  employed  at  the  heads  of  the  Del  Norte,  Monte  Vista,  and 
other  canals  in  the  San  Luis  valley  of  Colorado,  is  partly  open 
and  partly  closed.  An  earth  bank  or  dam  is  built  for  a  portion 
of  the  way  across  the  stream  and  of  such  height  that  it  will  not 
be  topped  by  floods.  The  remainder  of  the  weir  consists  of  a 
framework  of  rough-hewn  logs  founded  on  piles  with  openings 
between  into  which  horizontal  planks  or  flashboards  can  be  in- 
serted one  at  a  time. 

A  more  common  type  of  frame  or  flashboard  weir  is  that  em- 
ployed on  the  Kern  River  in  California.  (Plate  IV.)  An  ex- 
ample of  this  is  the  weir  at  the  head  of  the  Calloway  canal 
(Fig.  29),  which  consists  of  100  bays,  each  separated  by  a  simple 
open  triangular  framework  of  wood  founded  on  piles,  the  width 
of  each  opening  or  bay  being  4  feet.  Two  and  one-half  feet  below 
the  bed  of  the  stream  is  a  floor,  with  walls  about  2  feet  in  height, 


1 70 


HEADWORKS   AND   DIVERSION   WEIRS 


forming  compartments  filled  with  sand  on  which  the  waters  fall. 
This  apron  is  carried  up-  and  down-stream  for  a  distance  of  about 
10  feet  in  each  direction.  The  weir  proper  is  formed  of  frames  or 
trusses  of  6  by  6  inch  timber,  placed  transversely  4  feet  apart. 
These  frames  consist  of  2  pieces,  the  up-stream  piece  being  15 
feet  2  inches  long  and  set  at  an  angle  of  38  degrees,  while  the  other 
supports  it  at  right  angles  and  is  9  feet  4  inches  long.  The  lower 


FIG.  29. — Cross-section  of  Open  Weir,  Galloway  Canal. 

ends  of  these  rafters  thrust  against  two  pieces  of  6  by  2  inch  timber 
running  the  whole  length  of  the  weir  and  nailed  to  the  flooring. 
These  frames  are  supported  directly  on  anchor  piles,  one  at  each 
end  joiced  into  the  framing.  These  trusses  are  kept  in  vertical 
position  by  means  of  a  footboard  running  transversely  the  entire 
width  of  the  stream.  On  the  up-stream  face  of  the  trusses  planks 
or  flashboards  which  slide  between  grooves  formed  by  nailing 
face-boards  on  the  trusses  are  laid  on  to  the  required  height.  This 
weir  is  10  feet  in  height  above  the  wooden  floor,  which  is  flush 
with  the  river  bed . 

1 68.  Open    Masonry    Weirs,    Indian    Type. — A    substantial 


OPEN    MASONRY    WEIRS,    INDIAN    TYPE  171 


NARORA    WEIR- LOWER    GANGES   CANAL 
length   1260 metres 


ofSiver 


OKHLA   WEIR-AGRA     CANAL. 
Length 


DEHREE    WEJR-SOANE  CANAL 

Length  3825  metres 


OEZWARA     WEIR  -  KISTNA  CANAL. 
Length  J150  metres. 

" -tr "*-• 


600IVERY         WEIR. 


•>%T»'A:£V< 

PLATE  V. — Cross-sections  of  Indian  Weirs. 


172  HEADWORKS    AND    DIVERSION    WEIRS 

form  of  open  masonry  weir  is  that  generally  constructed  on  Indian 
rivers,  where  the  banks  and  bed  are  of  sand,  gravel,  or  other 
unstable  material.  These  weirs  generally  rest  on  shallow  founda- 
tions of  masonry,  in  such  manner  that  they  practically  float  on 
the  sandy  beds  of  the  streams.  The  foundation  of  such  a  weir  is 
generally  of  one  or  more  rows  of  wells  sunk  to  a  depth  of  from  6 
to  10  feet  in  the  bed  of  the  river,  the  wells  and  the  spaces  between 
the  rows  of  wells  being  filled  in  with  concrete,  thus  forming  a 
masonry  wall  across  the  channel.  A  well  or  block  is  a  cylindrical 
or  rectangular  hollow  brick  structure,  which  is  built  upon  a  hard 
cutting  edge  like  a  caisson,  and  from  the  interior  of  which  the  sand 
is  excavated  as  it  sinks.  After  it  has  reached  a  suitable  depth  it 
is  filled  with  concrete,  the  whole  depending  for  its  stability  on 
the  friction  against  its  sides.  This  form  of  construction  is  illus- 
trated in  Plate  V. 

The  weir  at  the  head  of  the  Soane  canals,  which  is  typical  of 
this  class  of  structure,  consists  of  three  parallel  lines  of  masonry 
running  across  the  entire  width  of  the  stream,  and_  vary  ing  from 
2j  to  5  feet  in  thickness.  The  main  wall,  which  is  the  upper  of 
the  three  and  the  axis  of  the  weir,  is  5  feet  wide  and  8  feet  high, 
and  all  three  lines  of  walls  are  founded  on  wells  sunk  from  6  to  8 
feet  in  the  sandy  bed  of  the  river.  Between  these  walls  is  a  simple 
dry  stone  packing  raised  to  a  level  with  their  crests,  thus  forming 
an  even  upper  surface.  The  up-stream  slope  is  i  on  3,  and  the 
down-stream  slope  i  on  12,  the  total  length  of  this  lower  slope 
being  104  feet,  while  the  total  height  of  the  weir,  including  its 
foundation,  is  19.3  feet. 

The  Soane  weir  has  a  total  length  across  stream  of  12,480 
feet,  of  which  1494  feet  consists  of  open  weir  disposed  in  three 
sets  of  scouring-sluices  (Fig.  30),  one  in  the  center  and  two  adja- 
cent to  either  bank  and  in  front  of  the  regulating  gates  at  the  head 
of  the  canals.  These  scouring-sluices  consist  of  three  parts— 
the  foundation,  the  floorway  or  apron,  and  the  superstructure. 
The  floor  is  deep  and  well  constructed  of  substantial  masonry, 
and  is  continued  for  a  short  distance  above  the  weir  and  for  a 
considerable  distance  below  it.  It  is  90  feet  wide  parallel  to  the 
river  channel,  and  is  founded  on  wells,  the  ashlar  pavement  of 


OPEN    MASONRY    WEIRS,    INDIAN    TYPE 

the  floor  being  15  inches  thick  in  the  bottom  of  the  scouring-sluices 
between  the  piers,  and  9  inches  thick  over  the  remainder  of  the 
apron.  Up-stream  from  the  sluice  floor  for  a  distance  of  25  feet 
is  a  line  of  wells  sunk  to  a  depth  of  16  feet  as  a  curtain- wall  to  the 
apron.  Twenty-five  feet  down-stream  from  the  flooring  of  the 
sluices  is  a  similar  line  of  wells  formed  into  a  wall,  and  the  spaces 


Elevation. 


CROSS  SECTION  OF  WEIR 
30'  -  *rt[— 


TO' 


FIG.  30. — Half-elevation,  Plan,  and  Section,  Soane  Weir,  India. 

between  these  two  curtain- walls  and  the  main  ashlar  flooring  of 
the  sluiceway  is  packed  with  dry-laid  bowlders  and  rubble  cov- 
ered with  a  pavement  of  masonry  9  inches  in  thickness.  Down- 
stream from  the  lower  curtain-wall  a  paving  of  large  bowlders 
stretches  for  50  feet  further,  the  whole  of  this  sluice  floor  parallel 
to  the  river  channel  being  200  feet  in  length.  This  is  a  typical 


174 


HEADWORKS   AND   DIVERSION    WEIRS 


floor  to  an  Indian  open  weir  or  sluiceway,  on  top  of  which,  in  line 
with  the  center  of  the  crest  of  the  weir,  are  built  up  masonry  piers 
at  intervals  of  from  6  to  12  feet  apart,  grooved  for  the  recep- 
tion of  planks  or  flashboards,  or  closed  with  lifting  or  automatic 
drop-gates. 

A  peculiar  form  of  open  weir  is  that  constructed  at  the  head  of 
the  Sidhnai  canal  in  India.  At  the  point  where  the  weir  is  built 
the  bed  of  the  river  gives  a  good  clay  foundation  for  a  short  dis- 
tance from  either  bank,  while  in  the  center  of  the  channel  the  bed 


FlG.  31. — Elevation  and  Cross-section  of  Sidhnai  Weir,  India. 

is  of  sand  for  a  considerable  depth.  Sheet  piling  10  feet  long  was 
driven  into  the  sandy  bed  of  the  river  to  prevent  excessive  per- 
colation. On  these  piles  (Fig.  31)  rests  a  series  of  piers  which 
support  masonry  arches,  the  piers  being  16  feet  between  centers 
and  filled  between  with  clay.  Above  this  masonry  arch  is  built  a 
continuous  wall  across  the  entire  width  of  the  stream  from  4  to  6 
feet  wide  on  top  and  from  3^  to  8J  feet  in  height.  Over  this 
wall,  parallel  to  the  channel  of  the  river,  is  built  a  masonry  floor- 
ing, the  upper  slope  of  which  is  i  on  3,  while  its  lower  slope 
varies  between  i  on  5  and  i  on  10,  according  as  it  is  near  the 
center  or  ends  of  the  weir.  The  total  width  of  this  floor  parallel 


LACUNA   WEIR,    COLORADO   RIVER  175 

to  the  channel  of  the  stream  is  12  feet  above  the  axis  of  the  weir 
and  40  feet  below  it,  the  lower  toe  terminating  in  a  series  of  wells. 
On  top  of  this  flooring  are  erected  a  series  of  piers  23  feet  apart 
between  centers,  and  projecting  2\  feet  up-stream  from  the  cen- 
tral wall  and  9  feet  down-stream,  their  total  length  parallel  to 
the  channel  being  15 \  feet  and  their  width  on  top  6  feet.  The 
crests  of  these  pillars  are  6 \  feet  in  height  above  the  crest  of  the 
floor,  while  the  total  height  of  the  weir  above  the  summit  of  the 
pile  foundation  is  about  21  feet.  It  will  thus  be  seen  that  this  weir 
offers  a  clear  waterway  across  the  entire  channel,  obstructed  only 
by  the  piers,  which  are  6J  feet  above  the  stream-bed.  The  open- 
ings between  these  piers  are  closed  by  means  of  needles,  which 
consist  of  a  heavy  beam  laid  along  the  crest  wall  from  pier  to  pier, 
against  which  rest  wooden  sticks  or  needles  inclined  at  a  slight 
angle.  These  needles  are  each  7 J  feet  long  by  5  inches  wide  and 
3J  inches  in  thickness,  and  are  laid  along  the  upper  face  close 
together  so  as  to  form  a  close  paling  or  barrier  when  in  place. 

169.  Laguna  Weir,  Colorado  River.— This  weir  was  con- 
structed across  the  Colorado  River  at  a  point  where  the  bed  of 
that  river  is  composed  of  sand  too  deep  to  permit  of  founding  the 
same  upon  solid  rock.  The  weir  was  designed  on  lines 
similar  to  those  on  which  like  structures  have  been  built  in  India 
and  Egypt.  (Art.  168.)  Its  maximum  length  is  over  4900 
feet,  extreme  height  above  stream-bed  19  feet.  It  consists  of 
three  walls  across  the  river-bed  (Fig.  32  ),  each  5  feet  wide,  one 
on  the  crest  line  19  feet  high,  the  next  57^  feet  down-stream,  14 
feet  high,  the  third  93^  feet  further  down-stream,  7  feet  high. 
On  the  up-stream  face  are  large  rubble  blocks  carefully 
placed  on  a  slope  2  to  i  from  the  crest  to  the  stream  bed. 
Down-stream  between  the  walls  is  a  loose  rock-fill  of  large 
blocks  surfaced  with  a  paving  24  to  36  inches  deep  of  hand-laid 
blocks.  The  slope  of  the  upper  surface  is  12  to  i.  Below 
the  lower  concrete  wall  is  an  apron  of  large  rubble  blocks, 
the  whole  resting  on  the  sand-bed  of  the  river.  Under  the  crest- 
line  wall  is  a  row  of  sheet  piling  driven  10  feet  below  the 
stream-bed.  This  is  built  up  of  three  2 — 1 2-inch  Oregon 
pine  planks,  thoroughly  spiked  and  clinched  by  one  spike  per 


i76 


HEADWORKS    AND    DIVERSION    WEIRS 


square  foot,  each  of  wrought  iron  7 
inches  long  and  3  inches  in  diameter. 
These  piles  are  sheared  obliquely  to 
make  them  mesh  closely  when  driven. 

The  rock-fill  is  composed  of 
stone  of  a  regular  shape  and  size,  the 
run  of  quarry,  at  least  two-thirds  of 
which  are  not  less  than  1000 
pounds  in  weight,  and  one-half  of  these 
not  less  than  4000  pounds  in  weight, 
the  whole  dumped  into  place  by 
dropping  from  an  elevation  of  not  less 
than  5  feet.  Small  stones  and  chips 
were  thrown  into  the  open  spaces  be- 
tween the  larger  slopes,  and  the  whole 
levelled  off  before  placing  pavements. 
All  paving-blocks  are  roughly  rec- 
tangular, none  less  than  2  feet  in 
length,  of  which  10  per  cent  are  3 
feet  long,  the  breadth  not  less 
than  i  foot  and  the  thickness  not  less 
than  J  foot.  This  paving  is  set  by 
hand,  closely  packed  and  well  tamped, 
no  stone  projecting  over  3  inches 
above  the  piling  and  surface,  and  no 
portion  laid  under  water. 

In  the  walls  of  the  weir,  as  well  as 
in  the  walls  and  piers  of  the  regulators 
and  sluiceways,  only  the  best  concrete 
was  used,  consisting  of  Portland 
cement,  i  barrel  to  3  barrels  of  \-  inch 
mesh  river-sand  and  7  barrels  full  of 
gravel  or  broken  stone,  the  latter  not 
exceeding  in  dimensions  one-half  the 
thickness  of  the  wall  in  which  it  was 
used. 

170.  Movable  Iron  Weirs,  French 


I 

8 


i; 


ROLLING    LIFT    WEIR 


177 


Type. — The  weirs  on  the  River  Seine  in  France  differ  materially 
from  the  open  Indian  weirs.  They  consist  of  a  series  of  iron 
frames  of  trapezoidal  cross-section,  somewhat  similar  in  shape  to 
the  frames  of  the  open  wooden  flashboard  weirs  of  California. 
On  these  frames  rest  a  temporary  footway,  and  on  their  upper 
side  is  placed  a  rolling  curtain  shutter  or  gate  which  can  be 
dropped  so  as  to  obstruct  the  passage  of  water  across  the  entire 
channclway  of  the  stream,  or  can  be  raised  to  such  a  height  as 
to  permit  the  water  to  flow  under  them.  In  times  of  flood  the 


FIG.  33. — View  of  Open  Weir  on  River  Seine,  France. 

curtain  can  be  completely  raised  and  removed  on  a  temporary 
track  to  the  river  banks,  the  floor  and  track  can  then  be  taken 
up,  leaving  nothing  but  the  slight  iron  frames,  which  scarcely 
impede  the  discharge  of  the  river  and  permit  abundant  passage- 
way of  the  floods  over,  around,  and  through  them  (Fig.  33). 

171.  Rolling  Lift- Weir. — An  interesting  type  of  movable  dam 
was  recently  constructed  at  Schweinfurt,  Bavaria.  As  described 
and  illustrated  in  Engineering  News  (Fig.  34)  it  consists  of  a 
heavy,  hollow,  riveted,  sheet-steel  cylinder,  6.5  feet  in  diameter 
and  121.3  feet  m  length,  resting  on  top  of  a  masonry  weir.  At 
each  end  of  the  upper  periphery  is  fixed  a  toothed  wheel  which 


178  HEADWORKS   AND    DIVERSION   WEIRS 

meshes  in  an  inclined  rack  built  in  each  abutment.  The  steel 
is  i.i  inches  thick,  built  in  sections  9.8  feet  long,  with  a  single 
longitudinal  joint.  The  transverse  joint  ends  are  butt-joints, 
and  each  section  is  reinforced  in  the  middle  by  a  brace. 

This  cylinder  is  water-tight  excepting  two  chambers  in  the 
upper  end  of  each  extremity.  When  the  down-stream  level  does 
not  rise  more  than  3  feet  above  the  bottom  of  the  dam,  the  weight 
of  the  cylinder  is  sufficient  to  counteract  the  pressure,  but  when 


FIG.  34. — Rolling  Lift-weir,  Schweinfurt,  Bavaria. 

the  back-water  level  rises  above  this  it  enters  the  two  chambers, 
thus  adding  to  the  stability  of  the  cylinder. 

The  racks  are  inclined  at  an  angle  of  45  degrees  along  the 
upper  part,  and  with  increasing  pitch  toward  the  bottom  with  a 
maximum  of  4  to  i,  the  radius  of  incline  being  4.5  feet,  thus  add- 
ing to  the  better  bearing  against  water  pressure  tending  to 
raise  it.  The  weight  of  the  cylinder  is  193,600  pounds.  The 
operating  apparatus  includes  two  steel  cables  of  1.8  inches  in 


WOODEN    CRIB   AND   ROCK   WEIRS  179 

diameter,  rolled  on  drums  and  operated  by  an  electric  motor. 
The  speed  of  lifting  the  cylinder  to  a  height  of  13.1  feet  or  above 
highest  flood  water  is  1 5  minutes.  By  auxiliary  gearing  through 
cranks  the  apparatus  may  be  worked  by  hand. 

172.  Construction  of  Crib  Weirs. — A  crib  weir  should  never 
be  left  hollow,  as  was  the  upper  part  of  the  old  Holyoke  weir 
(Fig.  37),  but  should  be  completely  filled  in  with  gravel  or  rock. 
Many  engineers  advise  against  rock  filling,  as  this  permits  the 
passage  of  air  to  the  wood,  and  thus  promotes  its  decay.     The 
action  of  air  in  causing  decay  is  still  more  marked  if  the  weir  is  left 
hollow.     Gravel  well  puddled  around  the  woodwork  becomes 
air-tight,  and  protects  every  timber  which  it  encases.     This  ma- 
terial is  therefore  the  most  desirable  filling.     A  timber  weir  is 
quite  permanent  when  it  is  constantly  submerged,  as  then  only 
the  apron  will  need  repair.     The  shape  of  such  a  weir  should 
always  be  such  as  to  prevent  the  water  which  falls  over  it  from 
excavating  beneath  its  toe,  especially  if  the  foundation  is  of  gravel 
or  soft  rock.     In  such  cases  a  roller  apron  should  be  built,  backed 
still  lower  down  by  a  horizontal  apron  which  will  take  up  the 
scouring  force  of  the  water.     Even  on  a  firm  rock  foundation  a 
clear  overfall  should  not  be  given  unless  a  deep  water-cushion  can 
be  furnished  or  the  bed  of  the  river  can  be  laid  dry  for  examina- 
tion and  repair  of  the  weir.     Timber  dams  are  usually  founded 
on  rock  or  gravel,  though  any  material  will  do.     When  founded 
on  soft  material  loose  rock  may  be  dumped  in,  or  piles  must  be 
driven  and  sheet  piling  be  used  to  prevent  underflow. 

173.  Wooden    Crib   and    Rock   Weirs. — This    type   of    weir 
is  generally  built  where  the  bed  and  banks  of  the  river  arc  of 
heavy  gravel  and  bowlders  or  of  solid  rock.     Crib  weirs  consist 
essentially  of  a  framework  of  heavy  logs,  drift-bolted  or  wired 
together,  and  filled  with  broken  stone  and  rocks  to  weight  and 
keep  them  in  place.     Such  works  may  be  founded  by  sinking  a 
number  of  cribs  one  on  top  of  the  other  to  a  considerable  depth 
in  the  gravel  bed  of  the  stream,  or  they  may  be  anchored  by 
bolting  them  to  solid  rock.     They  may  consist  of  separate  cribs 
built  side  by  side  across  the  stream  and  fastened  firmly  together 
as  in  the  old  weir  at  the  head  of  the  Arizona  canal  (Fig.  35),  or 


i8o 


HEADWORKS    AND   DIVERSION    WIERS 


they  may  be  made  as  one  continuous  weir,  as  the  structures  at 
the  heads  of  the  Kraft  Irrigation  District  canal  in  California, 
and  the  Bear  River  canal  in  Utah  (Fig.  36).  After  its  completion 
the  weir  is  planked  over  on  its  exposed  faces  and  forms  one  con- 
tinuous wall  across  the  channel  of  the  stream. 

The  old  weir  at  the  head  of  the  Arizona  canal  (Plate  VI) 
consisted  of  crib  boxes  of  hewn  logs  about  9  by  9  feet,  the  logs 
being  fastened  with  drift-bolts,  and  the  whole  wired  together 
and  filled  with  rocks.  This  weir  was  constructed  by  laying  mud- 
sills in  a  trench  excavated  in  the  bed  of  the  stream,  and  on  these 
was  built  up  the  cribwork.  In  the  central  and  deepest  portion 
of  the  river  channel  the  weir  was  sunk  to  a  depth  of  33  feet  in  the 
gravel  bed  of  the  stream,  while  its  crest  was  everywhere  10  feet 


f       •» 

FIG.  35. — Cross-section  of  Old  Arizona  Weir. 

above  mean  low-water.  The  base  of  this  weir  in  the  deepest 
part  of  the  channel  was  from  36  to  48  feet  in  width  parallel  to  the 
course  of  the  stream,  and  the  mudsills,  which  were  8  by  12  by  48 
feet,  were  wired  together  with  i-inch  cable  to  act  as  a  hinge  be- 
tween the  sections.  The  weir  was  built  in  four  sections  trans- 
versely to  its  axis  (Fig.  35).  The  whole  of  the  upper  surface 
was  planked  over  and  formed  a  series  of  steps  upon  which  the 
water  fell,  its  force  being  thus  broken.  This  weir  failed  in  a 
great  flood  in  1905  and  has  been  replaced  by  the  Granite  Reef 
weir  (Art.  188). 

The  crib  weir  at  the  head  of  the  Bear  River  canal  in  Utah  is 
370  feet  in  length  on  its  crest,  which  is  17 J  feet  in  maximum  height 
above  the  river  bed,  while  the  greatest  width  at  its  base  parallel 
to  the  course  of  the  stream  is  38  feet  (Fig.  36).  The  up-stream 
face  has  a  slope  of  i  on  2  while  that  of  the  down-stream  face  is 


182 


HEADWORKS   AND    DIVERSION    WEIRS 


i  on  J,  the  water  falling  on  a  wooden  apron  anchored  by  bolts  to 
the  bed-rock  of  the  river.  This  weir  consists  of  heavy  10  by  12 
timbers,  drift-bolted  to  the  rock  and  firmly  spiked  together.  The 
interstices  between  these  timbers  are  filled  with  broken  stone,  and 
it  is  backed  by  silt  deposited  from  the  river. 

The  old  crib  weir  across  the  Connecticut  River  at  Holyoke, 
Mass.,  was  about  1017  ft.  in  length,  its  ends  abutting  against 
heavy  masonry  wings  at  their  extremities.  Between  these  the 
crib  weir  was  composed  of  12  by  12  timbers,  built  in  such  a  way 
as  to  present  on  the  upper  face  a  surface  of  planking  inclined  at  an 
angle  of  21  degrees  to  the  horizon.  These  timbers  were  sepa- 


A  4  . 

FIG.  36. — Cross-section  of  Bear  River  Weir. 

rated  by  transverse  timbers  at  distances  of  6  feet  apart,  and  the 
whole  was  drift-bolted  to  the  solid  rock  of  the  channel.  The  crib- 
work  was  filled  with  loose  stone  to  a  height  of  about  10  feet,  and 
the  upper  surface  of  the  weir  was  planked  over.  On  the  upper 
toe  of  the  weir  rested  a  bed  of  concrete  to  prevent  seepage,  and 
over  this  was  a  filling  of  gravel  to  a  height  of  about  10  feet  (Fig. 
37).  The  down-stream  face  of  this  structure  consisted  of  an 
apron  or  roller-way  of  similar  crib  timbers,  a  little  more  substan- 
tially built. 

The  dam  built  by  the  Reclamation  Service  across  the  Yellow- 
stone River,  Montana,  for  diversion  of  the  Lower  Yellowstone 
canal  is  740  feet  long,  9  feet  in  height,  of  ogee  cross-section,  and  is 
built  of  wood  founded  on  piles  driven  into  the  clay  of  the  river 


SCOURING    EFFECT    OF    FALLING    WATER  183 

bed  (Fig.  38).  The  upper  toe  and  the  end  of  the  plank  floor 
which  extends  18  feet  below  the  lower  toe  are  protected  by  6" 
by  12"  sheet  piling  driven  15  to  20  feet  into  the  clay  bed.  The 
body  of  the  dam  and  below  the  down-stream  end  of  the  floor  are 
filled  with  heavy  rocks.  All  planking  and  framing  is  heavily 
drift-bolted  together  and  to  the  piles  by  i"  square  bolts  22  inches 
long.  The  planking  of  the  surface  is  of  8  by  12  to  10  by  12  inch 
material. 

174.  Scouring  Effect  of  Falling  Water. — In  the  construc- 
tion of  weirs  various  subterfuges  have  been  employed  to  deliver 
the  falling  water  so  quietly  that  it  shall  not  erode  the  stream-bed 
below.  The  erosive  force  of  falling  water  is  such  that  it  is  capa- 


0     4      8    IS    W   JO  14 


FIG.  37. — Cross-section  of  Old  Holyoke  Weir,  Mass. 

ble  of  wearing  away  even  the  hardest  rock.  The  principal  forms 
which  have  resulted  from  the  endeavor  to  reduce  this  action  are: 
i,  aprons;  2,  sloping  rollerways;  3,  ogee  curves  to  the  lower  tide 
of  the  weir;  4,  water-cushions.  Each  of  these  forms  has  its 
advocates,  and  each  is  especially  adapted  to  certain  conditions, 
dependent  chiefly  upon  the  height  of  overfall  and  the  character 
of  the  material  of  which  the  stream-bed  is  composed.  Under 
similar  conditions  aprons  are  employed  in  all  countries.  Ogee 
shapes  appear  to  have  originated  in  India,  and  are  very  popular 
there.  They  have  recently  been  adopted  extensively  in  this 
country. 

175.  Weir  Aprons. — Where  the  foundation   of   the   weir  is 
of  unstable  material,  as  earth,  sand,  or  gravel,  an  apron  is  built 


HEADWORKS    AND    DIVERSION    WEIRS 


below  its  down-stream  toe. 


Aprons  are  made  of  wood,  of  dry- 
laid  masonry,  of  cement  ma- 
sonry, of  concrete,  of  reinforced 
concrete  or  of  steel.  They  form 
a  substantial  artificial  flooring 
to  the  stream-bed  on  which  the 
force  of  the  falling  water  is  taken 
up,  thus  protecting  it  from  ero- 
sion and  preventing  undercut- 
ting of  the  weir.  Where  an 
apron  is  employed,  the  weir  de- 
pends on  its  efficient  construc- 
tion and  careful  maintenance 
for  its  security.  Such  works  are 
built  of  masonry  in  the  most 
substantial  manner  in  India, 
where  a  rough  general  rule  is  to 
give  the  masonry  apron  a  thick- 
ness equal  to  one-half  and  a 
length  parallel  to  the  stream 
channel  equal  to  from  three  to 
four  times  the  vertical  height  of 
the  obstructive  part  of  the  weir. 
Beyond  this  a  loose  stone  apron 
is  generally  added,  with  a  length 
equal  to  one  and  one-half  times, 
and  a  depth  equal  to  two-thirds 
of  the  height  of  the  weir.  An- 
other rule  adopted  in  India  is  to 
give  the  apron  a  length  equal 
to  from  six  to  eight  times  the 
square  root  of  the  maximum 
depth  of  water  above  the  weir 
crest,  and  a  thickness  equal  to 
one-fifth  to  one-fourth  of  the 
overfall  height  of  the  weir  plus 
the  depth  of  water  on  the  crest. 


ROLLERWAY    AND    OGEE-SHAPED    WEIRS  185 

According  to  the  American  standards  both  of  these  rules 
seem  to  give  unnecessarily  substantial  results.  With  us  wooden 
aprons  are  generally  employed  which  rarely  exceed  from  2  to  6 
feet  in  thickness  for  the  greatest  height  of  overfall.  Aprons, 
however,  cannot  be  used  with  security  with  weirs  in  which  the 
drop  is  considerable.  No  limit,  other  than  that  of  expense,  can 
be  set  to  the  height  for  which  aprons  are  serviceable,  for  a  point 
is  ultimately  reached  where  an  ogee-shaped  or  rollerway  weir  or 
a  water-cushion  will  be  less  expensive  and  more  serviceable. 

176.  Rollerway  and  Ogee-shaped  Weirs. — Ogee-shaped  weirs 
probably  originated  as  a  development  of  roller  aprons.  The  first 
ogee  weirs  of  any  magnitude  were  those  built  on  the  falls  in  the 
eastern  Jumna  canal  in  India.  The  original  sloping  apron  or 
rollerway  is  still  largely  employed,  the  chief  objection  to  it  being 


FIG.  39. — Diagram  of  Ogee  Curve. 

the  amount  of  material  required  in  its  construction  and  its  conse- 
quent cost.  Such  structures  are  the  weirs  of  the  Soane  and  Agra 
canals,  illustrated  in  Plate  V.  In  these  the  lower  slope  of  the  weir 
is  made  extremely  flat,  so  that  the  friction  of  the  water  rolling 
over  it  shall  retard  its  velocity  and  diminish  its  erosive  action.  In 
our  own  country  a  similar  long  sloping  rollerway  is  that  on  the 
old  Holyoke  weir  (Fig.  37). 

The  ogee  shape  is  an  improvement  on  the  rollerway.  It 
reduces  to  a  minimum  the  amount  of  material  required,  while 
producing  nearly  the  same  effect.  The  object  of  the  ogee  shape 
is  to  cause  the  water  to  slide  instead  of  to  fall  over  the  weir,  and 
the  exact  moment  when  water  ceases  to  slide  and  commences  to 
fall  is  shown  by  its  losing  its  bluish  color  and  commencing  to 
become  whitish.  The  ogee  curve  is  best  understood  from  the 


i86 


HEADWORKS   AND    DIVERSION   WEIRS 


accompanying  diagram  (Fig.  39).  Bisect  AE,  and  from  the  point 
of  bisection  at  a  draw  a  perpendicular  cutting,  the  perpendicular 
let  fall  from  A  at  C.  Join  C  E  and  prolong  this  line  until  it  cuts 
the  perpendicular  projected  on  B  at  D.  From  the  points  C  and 
D  as  centres,  draw  curves  of  the  ogee. 


2 

AB 


— > 


Excellent  examples  of  rollerway  weirs  with  ogee-shaped  curves 
are  illustrated  in  Fig.  40  and  in  Plates  VII  and  VIII,  and  ex- 
amples of  storage  dams  with  wide  crests  and  curved  overfalls  in 
Chapter  XVII. 

On  the  Ganges  canal  it  was  found  that  the  ogee  form  of  weir 
was  not  entirely  satisfactory.  The  shock  of  the  falling  water 
proved  so  great  as  to  materially  injure  the  structure,  and  all  of 
these  ogee  falls  have  since  been  remodelled  in  such  a  manner  as 


1,  Austin,  Tex., 
Z,  Herschel, 

3,  Waters, 

4,  Francis  &  Kendall, 
S^Leffel, 

6,  Newton,  30  ' 

7,  Mechanicsvflle,  N.T.,  16  4 

8,  Croton,  38  ' 


60  ft.  high. 
80  « 
SO  " 
30  " 


FIG.  40. — Cross-sections  of  Eight  Ogee -shaped  Weirs. 

to  form  water-cushions.  Thus  on  falls  15  feet  high  the  ogee  has 
been  cut  so  as  to  give  first  a  vertical  fall  of  5  feet  to  a  short  level 
bench  10  feet  in  length,  then  a  vertical  drop  of  10  feet  ending  in  a 
shallow  water-cushion  the  floor  of  which  is  of  masonry  4  feet 
in  thickness. 

177.  Water-cushions. — The  principle  involved  in  the  water- 
cushion  is  that  which  nature  has  laid  down  for  herself  on  all 


WATER-CUSHIONS  187 

natural  falls,  namely,  that  of  having  a  deep  enough  cistern  below 
the  fall  to  take  up  the  shock  of  the  falling  water  and  reduce  its 
velocity  to  the  normal.  Cataracts  and  falls  erode  a  cistern  the 
depth  of  which  bears  a  certain  relation  to  the  height  of  the  fall. 
The  method  of  constructing  a  water-cushion  is  not  to  excavate 
such  a  cistern  below  the  weir,  but  to  create  a  corresponding  depth 
by  building  a  low  subsidiary  weir  below  the  upper  weir.  This 
subsidiary  weir  backs  the  water  up  against  the  lower  toe  of  the 
main  weir  to  the  required  depth,  at  the  same  time  practically 
reducing  the  height  of  the  fall  by  the  height  of  the  subsidiary  weir. 
It  is  difficult  to  find  any  set  rule  for  determining  the  depth  of 
water-cushion  for  a  given  height  of  fall.  From  observations  of 
several  natural  waterfalls  it  has  been  discovered  that  the  height 
of  fall  is  to  the  depth  of  the  water-cushion  as  from  5  or  7  to  i.  In 
an  experimental  fall  constructed  on  the  Ban  Doab  canal  in  India 
it  was  found  that,  with  a  height  of  fall  to  a  depth  of  water-cushion 
as  3  to  4,  the  water  had  no  injurious  effect  on  the  bottom  of  the 
well.  On  canals  where  the  height  of  fall  is  not  great  it  has  been 
discovered  that  the  depth  of  the  water-cushion  may  be  approxi- 
mately determined  from  the  formula  D=  c\/ '  h*\/ '  d,  in  which  D 
represents  the  depth  of  the  water-cushion  below  the  crest  of  the 
retaining  wall ;  c  is  a  coefficient,  the  value  of  which  is  dependent 
on  the  material  which  is  used  for  the  floor  of  the  cushion  and 
varies  between  .75  for  compact  stone  and  1.25  for  moderately 
hard  brick;  h  is  the  height  of  the  fall,  and  d  is  the  maximum 
depth  of  water  which  passes  over  the  crest  of  the  weir.  The 
breadth  of  the  floor  or  the  bottom  of  the  cistern  of  the  water- 
cushion  parallel  to  the  stream  channel  is  dependent  on  the  sec- 
tion of  the  weir  and  will  not  exceed  Sd  and  should  not  be  less  than 
6d.  A  rule  laid  down  for  determining  the  dimensions  of  water- 
cushions  and  their  cisterns  on  the  smaller  canals  in  India  is  that 
the  depth  of  the  cistern  at  the  foot  of  the  weir  shall  equal  one- 
third  of  the  height  of  the  fall  plus  the  depth  of  water.  Thus  on 
a  fall  4  feet  deep  on  a  canal  carrying  5  feet  of  water  the  cistern 
depth  will  equal  J  (4  +  5)  =3  feet.  The  minimum  cistern  length 
is  equal  to  three  times  the  depth  from  the  drop-wall  to  the 
reverse  slope  x>f  the  cistern,  which  latter  will  be  i  in  5.  The 


••vr;.;-'  •% 

1 88  HEAD  WORKS    AND    DIVERSION    WEIRS 

width  of  the  cistern  must  be  twice  the  mean  depth  of  the  water 
in  the  channel. 

The  Reclamation  Service  has  adopted  the  water-cushion, 
combined  in  some  cases  with  the  notched  crest  and  gratings,  for 
drops  on  a  number  of  canals,  including  the  Interstate  canal,  Neb.- 
Wyo.,  and  Uncompahgre  canal,  Col.  (Art.  223  and  224). 

In  this  country  a  few  weirs  have  been  designed  and  constructed 
with  a  partial  ogee  curve  to  the  lower  face,  the  water  dropping 
into  a  water-cushion.  The  most  notable  of  these  are  the  great 
weirs  at  the  head  of  theTurlock  and  Modesta  canals  in  California 
(Article  356)  and  the  Spier's  Falls  dam  (Art.  359).  A  water- 
cushion  15  feet  in  depth  is  obtained  below  this  weir  by  the  con- 
struction of  a  subsidiary  weir  20  feet  in  height,  placed  at  a 
distance  of  200  feet  below  the  main  weir.  The  height  of 
overfall  from  the  main  weir  is  98  feet,  thus  giving  a  ratio  of 
depth  of  water-cushion  to  height  of  overfall  of  about  i  in  6.  In 
the  case  of  this  weir,  however,  its  down-stream  face  is  not  made 
vertical,  but  is  made  somewhat  after  the  design  which  would  be 
obtained  by  using  one  of  the  gravity  formulas  and  adding  to  this 
sufficient  material  to  produce  the  ogee  curve. 

The  Indian  method,  which  has  proved  very  satisfactory  in 
practice,  is  well  illustrated  in  the  Vir  weir  (Article  184)  and  the 
Betwa  dam  (Article  355).  In  each  of  these  the  water  is  permit- 
ted a  clear  vertical  overfall  to  the  water-cushion,  the  weight  neces- 
sary to  give  the  weir  stability  being  obtained  by  increasing  its 
cross-section  on  the  up-stream  side.  In  both  of  these  cases  sub- 
sidiary weirs  are  constructed  at  some  distance  below  the  main 
weir  in  the  rock  bed  of  the  river,  which  backs  up  the  water  to  the 
required  height  on  the  toe  of  the  main  weir.  A  subsidiary  weir 
of  a  form  somewhat  similar  to  that  below  the  Vir  weir  is  illus- 
trated in  Fig.  171.  This  weir  is  employed  below  the  main  escape 
weir  of  the  Periar  dam  in  India  to  form  a  water-cushion  on  which 
the  floods  fall. 

178.  Masonry  Weirs. — For  permanent  weirs  on  stable  foun- 
dations only  masonry  and  steel  should  be  used.  It  is  frequently 
necessary,  however,  to  build  weirs  of  less  durable  material,  the 
object  being  to  economize  on  the  first  cost,  or  because  the  founda- 


OP  TMI 

UNIVERSITY 

Of  y  MASONRY    WEIRS  l8o 

FORjJJ^X 

tion  will  not  safely  support  a  masonry  structure.  Masonry  weirs 
may  be  built:  i,  of  reinforced  concrete;  2,  of  plain  concrete;  3, 
of  uncoursed  rubble  in  cement;  4,  of  ashlar;  5,  of  brick;  and 
6,  of  various  combinations  of  these,  including  loose  packed,  un- 
cemented  rubble  retained  in  place  by  masonry  walls. 

Masonry  weirs  may  be  classified  according  to  the  superstruc- 
ture as  follows:  first,  simple  weirs  with  a  clear  overfall  to  the 
stream-bed;  second,  simple  weirs  with  clear  overfalls  to  an 
artificial  apron;  third,  weirs  with  rollerway  on  lower  face;  fourth, 
weirs  with  heavy  cross-section  and  ogee  shape;  fifth,  weirs  with 
clear  fall  to  water-cushion. 

The  principal  classification  of  masonry  weirs  is  dependent  on 
the  foundation.  Where  practicable  such  structures  should  only 
be  founded  on  firm  rock,  but  occasionally  the  depth  of  this  below 
the  surface  is  so  great  as  to  render  it  necessary  to  found  the  weir 
on  gravel  or  sand.  Classified  according  to  their  substructure, 
masonry  weirs  may  be  of  the  following  types:  i,  founded  on  piles; 
2,  founded  on  piles  and  rock  cribs;  3,  founded  on  masonry  wells 
or  caissons;  and  4,  founded  on  rock. 

Masonry  weirs  are  usually  given  a  batter  on  the  up-stream 
face  of  i  to  2  inches  per  foot.  The  lower  face  may,  according  to 
the  height  of  the  structure,  i,  be  given  a  slight  batter;  2,  have  a 
parabolic  or  ogee  curve  to  diminish  erosive  action;  or  3,  be  given 
a  batter  of  i  on  3  to  5  and  be  built  in  steps  to  break  up  the  force 
of  the  falling  water.  The  curved  face  reduces  the  shock  on  the 
dam,  but  permits  of  erosive  action  on  the  foundation  below  the 
toe.  The  stepped  face  is  well  suited  to  floods  of  small  volume, 
but  is  less  effective  with  floods  of  greater  amount. 

The  top  width  of  a  masonry  weir  should  not  be  less  than  5 
feet,  and  for  high  weirs  more  to  enable  them  to  resist  blows  from 
logs,  ice,  etc.  Capstones  should  be  dowelled  and  should  have  a 
downward  inclination  up-stream  to  ease  the  blows  received  from 
ice  and  floating  matter.  (Figs.  41,  43,  and  53.)  If  of  concrete 
this  should  be  well  reinforced  in  the  upper  third  for  the  same 
reason. 

Where  low  masonry  weirs  are  on  porous  foundations,  as  earth, 
loose  rock,  etc.,  earth  backing  is  sometimes  laid  on  the  up-stream 


i  go 


HEADWORKS   AND   DIVERSION   WEIRS 


face  to  the  crest  height  (Fig.  42).     This  should  have  slopes  of  i  on 
2  to  3,  as  with  an  earth  embankment.     If    of   less  porous  ma- 
terial than  the  foundation  and 
compactly  laid,  such  a  back- 
ing may  add  materially  to  the 
safety  of  the  weir  by  reducing 
the  percolation  under  it. 

179.  Masonry  Weirs 
founded  on  Piles. — In  the  con- 
struction of  masonry  weirs  in 
gravel  or  earth,  it  is  usual  to 
found  the  weir  on  piles  driven 
deep  into  the  river  -  bed. 
These  may  be  of  wood,  of 
steel  or  of  concrete.  In  a  few 
instances  cribs  and  caissons 
have  been  sunk  for  founda- 
tions. In  India  the  usual 
foundation  in  unstable  ma- 
terial is  the  "well"  (Article 
182). 

The    Leasburg    diversion 
weir  on  the  Rio  Grande,  N. 
M.,  project  of  the  Reclama- 
tion  Service  is  of   reinforced 
concrete.     It  is  600  feet  long 
and  30  feet  wide,  founded  on 
piles  and  sheet  piling  driven 
to  a  depth  of  25  feet  in  the 
sand   of    the    river-bed.      At 
one  end  it  abuts  against  solid 
rock,  and  at  the  other 
against     a     concrete 
pier,  whence  1600  feet 
of  earth  embankment 
extend  across  the  river 
bottom.  (Fig.4i.)  The 


MASONRY   WEIR    FOUNDED    ON   PILES   AND   CRIBS      IQI 

weir  proper  is  actually  but  9  feet  high  and  2  feet  wide  on  the 
crest,  sloping  on  the  down-stream  side  with  a  reversed  curve  to  a 
broad  reinforced  concrete  apron  2  feet  thick,  founded  on  piles, 
and  23  feet  broad. 

The  weir  of  the  Norwich  Water  Power  Company  across  the 
Shetucket  River  in  Connecticut  is  a  good  example  of  a  weir 
founded  on  piles.  The  bed  of  the  river  at  the  site  of  the  weir  is 
composed  of  gravel  containing  small  bowlders  and  is  30  feet  or 
more  in  depth.  This  weir  (Fig.  42)  is  15  feet  wide  at  the  base 
and  7 J  feet  wide  on  top,  its  maximum  height  being  about  20  feet. 
It  is  constructed  of  rubble  masonry  with  a  cut-stone  coping-wall. 


FIG.  42. — Cross-section  of  Norwich  Water  Power  Company's  Weir. 

The  upper  slope  is  covered  with  one  foot  of  concrete  faced  with 
planking  secured  to  it  with  long  iron  bolts.  The  up-stream  face 
has  a  batter  of  1 2  on  5  and  is  backed  by  an  earth  filling  having  a 
slope  of  about  i  on  i  J,  which  reaches  to  the  crest  of  the  weir.  A 
heavy  timber  apron  projects  down-stream  for  22  feet,  the  last  8 
feet  of  which  has  an  upward  pitch. 

1 80.  Masonry  Weir  founded  on  Piles  and  Cribs. — On  the 
Chicopee  River  in  Connecticut  is  a  weir  built  partly  on  rock  and 
partly  on  deep  gravel.  Its  cross-section  is  the  same  throughout 
and  is  similar  to  that  of  the  weir  just  described.  Where  the  river- 
bed is  composed  of  gravel  the  weir  rests  directly  on  a  depth  of  3 
feet  of  cribwork  filled  with  broken  stone.  Below  this  and  con- 
nected with  its  timber  foundation  is  an  apron  10  feet  in  length 


192  HEADWORKS    AND    DIVERSION    WEIRS 

which  rests  on  anchor  piles,  its  lower  extremity  being  protected 
by  a  row  of  sheet  piling. 

181.  Masonry   Weir   founded   on   Cribs. — One   of   the   most 
interesting  and  largest  masonry  weirs  founded  on  unstable  soil 
was  the  old  Croton  dam,  in  New  York.     This  was  constructed 
for  water-storage  but  acted  also  as  an  overfall  weir.     The  con- 
struction of  this  weir  was  peculiarly  composite,  a  large  portion 
resting  on  firm  rock,  the  remainder  being  founded  on  a  stratum 
of  alluvial  soil  containing  bowlders.     The  piers  (Plate  VI)  were 
of  timber  crib-work,  the  walls  of  which  were  connected  by  ties 
and  the  whole  filled  with  stone. 

This  structure  was  50  feet  in  maximum  height  and  76  feet  in 
maximum  width  at  the  base.  Its  up-stream  slope  was  vertical  for 
23^  feet,  broken  below  into  two  vertical  benches.  It  was  backed 
behind  by  an  earth  embankment  having  a  very  low  and  flat  slope. 
The  down-stream  face  had  an  ogee  curve.  The  crest  was  convex, 
with  a  radius  of  10  feet,  below  which  was  a  reverse  or  concave 
curve  with  a  radius  of  55  feet.  Below  the  lower  end  of  this  weir 
was  a  raised  apron  55  feet  in  total  length  and  connected  with  the 
main  weir.  The  rise  of  this  apron  was  i  in  nj,  and  the  amount 
of  this  rise  was  2 J  feet,  giving  a  water-cushion  of  this  depth  in  the 
lower  part  of  the  apron.  At  a  distance  of  300  feet  from  the 
extremity  of  this  apron  was  a  secondary  weir  of  crib  timber  filled 
with  broken  stone.  The  object  of  this  secondary  weir  was  to  divide 
the  head  of  water,  thus  causing  it  to  fall  in  two  steps,  the  first  38 
feet  in  height  to  the  lowest  part  of  the  apron,  and  the  second  15 
feet  in  height  over  the  secondary  weir  to  the  stream-bed.  This 
secondary  weir  answered  the  additional  purposes  of  creating  a 
shallow  water-cushion  at  the  foot  of  the  main  weir. 

182.  Masonry  Weirs  founded  on  Wells. — This  class  of  weir  is 
as  yet  peculiar  to  India,  where  it  is  built  on  sand  or  gravel  stream- 
beds.    In  PL  V  are  illustrated  several  examples  of  these  structures ; 
those  across  the  Soane  River,  India,  and  at  Yuma,  California,  are 
described  in  Articles  168  and  169.     They  consist  essentially  of 
one  or  more  walls  of  masonry  running  across  the  entire  width  of 
the  stream  and  founded  on  wells,  while  the  space  between  these 
is  filled  in  with  loose-packed  stone.     The  slopes  of  these  weirs 


MASONRY   WEIRS    FOUNDED  ON   WELLS 


193 


C 


194  HEADWORKS   AND    DIVERSION    WEIRS 

are  generally  long  and  low,  varying  between  vertical  and  i  on  3 
to  5  on  the  upper  face,  but  on  the  lower  face  ranging  from  i  to 
10  to  20.  In  the  case  of  the  weir  across  the  Ganges  River  at  the 
head  of  the  Lower  Ganges  canal,  the  main  obstruction  to  the 
stream  channel  is  a  masonry  wall  founded  on  wells.  On  the 
lower  or  down-stream  face,  however,  instead  of  the  usual  long 
slope  there  is  a  vertical  drop  of  gj  feet.  The  top  width  of  the 
wall  is  7  feet,  and  the  water  falling  over  this  drops  to  an  apron 
nearly  150  feet  long,  which  is  composed  of  masonry  resting  on 
four  rows  of  shallow  wells  for  a  distance  of  about  40  feet,  below 
which  a  loose  stone  apron  kept  in  place  by  rows  of  wells  extends 
for  the  remaining  1 10  f eet. 

183.  Concrete  Weir,  Ashlar  Facing. — The  Hen  ares  weir  in 
Spain — shown  in  cross-section  (Fig.  43) — is  23  feet  in  maximum 


FIG.  43. — Cross-section  of  Henares  Weir,  Spain. 

height,  its  upper  slope  having  a  batter  for  the  lower  two-thirds 
of  about  6  on  i,  and  for  the  upper  third  of  12  on  i.  Its  top 
width  is  3.14  feet,  its  thickness  at  the  base  is  45.8  feet,  and  its 
face  has  an  easy  flat  ogee-shaped  curve.  This  weir  is  390  feet  in 
length  on  the  crest,  being  curved  in  plan  and  running  obliquely 
across  the  river  at  a  tangent  to  the  axis  of  the  canal.  Its  body  is 
composed  of  concrete,  while  the  crest  and  lower  slope  are  faced 
with  cut  stone  blocks  alternating  in  headers  and  stretchers. 
Leakage  was  obviated  by  cutting  a  channel  in  the  rock  along  the 
central  axis  of  the  weir  for  its  entire  length,  and  in  this  is  fitted 
a  line  of  stone,  half  bedded  in  the  rock  and  half  in  the  concrete  of 
the  weir,  the  joints  being  run  with  pure  cement.  In  the  sides  of 
each  of  the  four  upper  courses  of  stones  near  the  crest  of  the  weir. 


RUBBLE    MASONRY    WEIR 


195 


were  cut  V-shaped  grooves,  and  expanding  horizontal  grooves 
were  cut  in  the  upper  and  lower  faces  of  each  stone,  forming  a 
continuous  channel  which  was  filled  with  pure  cement  so  as  to 
form  a  tight  joint  between  each  stone.  As  the  bed  of  the  river 
was  uneven,  the  lower  portion  of  the  weir  was  carried  down  as 
an  apron  by  means  of  a  series  of  blocks  of  stone  formed  in  steps, 
the  last  of  which  is  firmly  embedded  3  feet  in  the  rock. 

184.  Rubble  Masonry  Weir. — The  Yir  weir  at  the  head  of  the 
Nira  canal,  India,  is  built  of  uncoursed  rubble  masonry  and  is 
protected  by  a  water-cushion.  It  is  2340  feet  in  length,  43^-  feet 


FIG.  44. — Cross-section  of  Iron  Weir,  Cohoes,  X.  Y. 

in  height,  and  9  feet  wide  on  top,  and  is  constructed  of  un- 
coursed rubble  masonry.  The  down-stream  slope  is  8  on  i  for 
20  feet  from  the  crest  and  6  on  i  for  the  remainder  of  the  weir, 
while  the  up-stream  face  has  a  uniform  batter  of  20  on  i  and  at 
no  place  is  the  mean  thickness  of  the  weir  less  than  half  its  height. 
This  weir  is  founded  on  solid  rock,  and  in  order  to  form  a  water- 
cushion  a  subsidiary  weir  is  provided  2800  feet  below  the  main 
weir.  This  subsidiary  weir  is  located  in  a  narrow  portion  of  the 
river  channel,  its  total  length  being  615  feet,  its  height  24 J  feet, 
while  its  crest  is  20  feet  lower  than  that  of  the  main  weir,  thus 


196  HEADWORKS   AND   DIVERSION   WEIRS 

forming  a  permanent  water-cushion  20  feet  deep.  The  maxi- 
mum flood  which  is  estimated  to  pass  over  this  weir  is  158,000 
second-feet,  producing  a  depth  of  32  feet  in  the  water-cushion 
and  a  height  of  overfall  of  but  8  feet. 

185.  Iron  Ogee  Rollerway  Weir. — The  State  dam  across  the 
Mohawk  River  at  Cohoes,  N.  Y.,  was  remodelled  to  give  the 
down-stream  face  an  ogee  shape.     Iron  and  steel  were  used  to 
give  the  required  surface  instead  of  cut  masonry.     As  a  result 
a  substantial  face  and  apron  have  been  obtained  at  less  expense 
than  would  have  been  possible  with  ashlar  masonry.     Otherwise 
the  weir  is  practically  a  masonry  structure,  as  this  iron  facing  has 
been  placed  over  and  bolted  to  the  old  masonry  weir,  and  the 
latter  has  been  filled  up  with  concrete  to  the  surface  of  the  iron 
facing. 

The  total  length  of  this  weir  is  1611  feet  (Plate  VIII).  The 
facing  is  backed  by  strong  plate-girder  ribs  shaped  to  the  final 
contour  of  the  weir  (Fig.  44),  and  secured  by  bolts  and  braces  to 
the  masonry  work  of  the  old  structure.  Sheet  iron  is  secured  in 
grooves  in  these  ribs  so  as  to  fill  it  up  as  a  flush  and  smooth  face, 
and  concrete  has  been  rammed  in,  forming  a  solid  backing.  In 
constructing  this  weir  the  lower  half  of  the  apron  was  first  built 
and  the  space  between  the  iron  plates  and  the  masonry  filled  with 
the  concrete,  then  the  upper  half  was  built  in  the  same  manner 
and  the  concrete  carried  up  behind  the  iron  plates  at  the  top.  At 
the  foot  of  the  curved  rollerway  is  a  short  apron  of  heavy  plate 
iron  about  5  feet  in  length,  fastened  to  the  lower  girder  of  the 
rollerway  on  one  side  and  to  wooden  beams  let  into  the  rock  of 
the  river  bed  at  the  outer  end. 

The  framing  of  this  iron  weir  face  is  12^  feet  in  length  hori- 
zontally from  the  crest  of  the  weir  to  the  lower  end  of  the  roller- 
way,  while  the  top  of  the  coping  is  8  feet  4  inches  in  length  and 
slopes  back  with  a  fall  of  i  J  feet.  The  total  height  of  the  weir, 
from  the  crest  to  the  foot  of  the  rollerway,  is  10  feet  6  inches.  The 
coping  girder  is  8^  inches  deep  at  the  back  or  up-stream  end,  and 
1 8  inches  in  depth  at  the  crest-curve,  which  latter  has  a  radius  of 
2  feet  from  the  upper  end  of  the  crest-curve  or  coping. 

1 86.  Masonry  and  Iron  Drop-gate  Weir. — At  the  head  of  the 


MASONRY   AND    IRON    DROP-GATE   WEIR 


197 


feW  li  ''''  v  si 

]&&'/>     '  V0/     f  A  v*  ^  ,  1  /         '  i    •? 

iP^x/--' -f./!/'  '  j  ,}     ^     i<  NV  v  I       /     "y        /x 

^^fewiibv-l    r 

isS^y  fiDAvji^.  1      ' 


HEADWORKS    AND    DIVERSION    WEIRS 


Goulburn  irrigation  system  in  Australia  is  a  clear  overfall  weir 
for  combined  storage  and  diversion,  and  at  each  of  its  abutments 
there  heads  a  main  line  of  canal.  Its  available  storage  capacity  is 
about  1000  acre-feet,  though  it  is  expected  that  this  can  be  filled 
several  times  in  a  season.  On  the  crest  of  the  masonry  struc- 
ture are  built  up  iron  pil- 
lars between  which  slide 
lifting-gates  which  can  be 
raised  and  lowered  by  hy- 
draulic power,  and  add 
thus  to  the  diversion  height 
of  the  weir  and  furnish 
storage  capacity  equiva- 
lent to  this  height.  The 
highest  flood  known  in  the 
river  was  estimated  to 
discharge  50,000  second, 
feet,  and  the  wasteway 
capacity  furnished  between 
the  crest  of  the  masonry 
work  and  the  soffit  of  the 
overhead  bridge  is  capable 
of  passing  a  larger  volume. 
The  Goulburn  weir  is 
founded  on  alternate  beds 
of  sandstone,  slate,  and 
pipe-clay,  standing  almost 
vertically  on  edge.  This 
weir  is  of  sufficient  height 
to  raise  the  summer  level 
of  the  river  about  45  feet, 

FIG.  45. — Down-stream   Elevation,   Goulburn  ,    i       f  f 

Weir,  Australia.  Or     tO    a     total    of     5°    f  eet 

above  the  river  bed.     It  is 

695  feet  in  length,  exclusive  of  the  canal  regulators  at  either  end, 
which  have  a  further  length  of  masonry  work  of  230  feet.  The 
body  of  the  work  is  of  combined  concrete  masonry,  composed  of 
broken  stone,  sharp  grit,  and  Portland  cement,  backed  with 


MASONRY   AND   IRON   DROP-GATE    WEIR 


199 


stepped  granite.  In  the  portion  of  the  weir  across  the  natural 
waterway  of  the  river  were  six  temporary  tunnels  (Fig.  45),  each 
with  a  sectional  area  of  44  feet,  designed  to  carry  the  stream  flow 


~I33~r3 

FIG.  46. — Section  of  Goulburn  Weir,  Australia. 

of  about  3750  second-feet  during  construction.  These  were  filled 
in  with  masonry  after  the  completion  of  the  remainder  of  the 
work.  The  waterway  in  the  upper  portion  of  the  weir  above 


200 


HEADWORKS    AND    DIVERSION    WEIRS 


the  masonry  crest  is  composed  of  21  floodgates  (Plate  IX)  each 
having  a  clear  opening  of  20  feet  horizontally  and  10  feet  verti- 
cally. These  are  lowered  into  chambers  or  recesses  in  the  body 
of  the  structure  (Fig.  46),  and  can  be  so  adjusted  as  to  maintain 
the  water-level  in  front  of  the  canal  offtakes  at  the  normal  full- 
supply  level.  The  chambers  are  lined  with  skeletons  of  cast-iron 
ribs  between  strong  cement  mortar;  and  the  wall  in  front  of  each 
chamber  that  takes  the  pressure  of  the  water  is  strengthened  by  a 
series  of  rings  of  wrought  iron  built  into  the  concrete.  The 
gates  are  framed  with  wrought- iron  T  beams  filled  with  cast-iron 
plates,  and  weigh  7  tons  each.  They  are  worked  by  screw-gear- 
ing actuated  by  3oJ-inch  Leffel  turbines,  which  can  be  worked 
either  together  or  separately.  The  available  head  for  working 


FIG.  47. — Cross-section  of  Reinforced  Concrete  Weir,  Theresa,  N.  Y. 

them  varies  from  3  to  13  feet,  according  to  the  volume  of  water 
in  the  river,  and  they  give  from  3  to  27  horse-power.  Hand- 
gearing  is  provided  for  each  gate  in  case  of  emergency. 

187.  Reinforced  Concrete  Weir. — Recently  diversion  weirs  of 
moderate  height  have  been  constructed  of  reinforced  concrete. 
A  good  example  of  such  structures  is  one  at  Theresa,  New 
York,  which  has  a  total  length  of  120  feet  and  a  height  of  n  feet. 
It  consists  of  a  series  of  triangular  walls  or  buttresses  of  solid 
concrete,  each  12  inches  thick  and  spaced  6  feet  apart,  dowelled 
to  the  rock  on  which  they  rest  with  ij-inch  iron  pins  36  inches 
long.  They  support  an  inclined  deck  consisting  of  6  inches  of 
concrete  reinforced  with  Thatcher  steel  bars,  f  to  f  inch  in  di- 
ameter, spaced  6.3  to  7  inches,  center  to  center,  and  expanded 
metal  (Fig.  47).  The  crest  is  strengthened  with  a  6  X  8-inch 


REINFORCED    CONCRETE    WEIR 


201 


concrete  beam  reinforced  with  two  J-inch  steel  rods.  The  base 
of  the  spillway  or  toe  is  also  reinforced  with  a  triangular  block 
of  concrete  40  inches  wide.  The  buttresses  were  built  on  forms 
and  the  whole  work  completed  in  18  working  days. 

An  excellent  type  of  such  weir  is  that  built  by  the  Reclamation 
Service  for  the  diversion  of  the  Shoshone  River  into  the  Corbett 
tunnel.  This  weir  crosses  the  river  at  right  angles  with  a  crest 
length  of  400  feet  and  height  of  24  feet  (Fig.  48).  In  section 
it  is  a  truncated  triangle  with  an  up-stream  surface  of  reinforced 
concrete  2\  feet  thick,  resting  on  a  3^-foot  concrete  cutoff  wall, 


'0-  3*Z5tS*^^\**^^^f:A^**frta 

U&  b^e^^^^V'M'c^oX^U^^^fe^fe1 

f^\^^^^^^l:^^^^^^ 


E1.4607.0Ci-^U_ 

^^p- 

U  to  extend  SECTION  A-A 

3  into  bLul. 

FIG.  48. — Cross-section  of  Corbett  Weir,  Shoshone  Project,  Wyoming. 


and  having  a  slope  of  i  to  i.  The  lower  side  is  open  and  drops 
off  to  a  2-foot  reinforced  concrete  floor  which  extends  25  feet 
down-stream  to  a  cutoff  concrete  wall  3j-feet  thick.  Under  the 
point  where  the  falling  water  strikes  the  floor  is  a  third  foundation 
wall  3J  feet  wide  at  base  and,  like  the  others,  about  6  feet  in 
depth.  The  upper  slope  is  supported  at  intervals  of  12  feet  by 
reinforced  concrete  partition  walls  2  feet  in  thickness.  The  rein- 
forcing bars  are  of  f-  to  J-inch  square  steel  spaced  6  inch  centers. 
At  one  end  of  the  dam  is  a  sluiceway  of  21  feet  clear  opening 
divided  by  two  piers,  and  separated  from  the  weir  by  a  long 


202 


HEADWORKS    AND    DIVERSION    WEIRS 


concrete  training  wall  3^  feet  thick.  Adjacent  to  the  sluiceway 
is  the  head  of  Corbett  tunnel,  entrance  to  which  is  controlled  by 
two  6  feet  6  inches  regulating  gates  (Fig.  49). 

1 88.  Reinforced  Rubble  Masonry  Weir. — The  failure  of  the 
Arizona  dam  (Art.  173)  in  the  floods  of  1905  resulted  in  the 
acquirement  of  the  Arizona  and  related  canal  systems  by  the 
United  States  Reclamation  Service,  which  proceeded  at  once  to 


10  0  10  20 


FIG.  49. — Plan  of  Corbett  Dam  and  Headworks,  Shoshone  Project,  Wyoming. 

erect  a  permanent  masonry  diversion  weir.     At   this  structure 
head  the  main  north  and  south  side  canals,  which  carry  all  the 
water  for  the  Salt  River  project,  including  the  natural  flow  of 
the  river  and  the  water  stored  in  Roosevelt  reservoir  (Art.  360). 
The  Granite  Reefs  diversion  weir  (Fig.  50)  is  located  2  miles 


REINFORCED    RUBBLE    MASONRY    WEIR 


203 


below  the  old  Arizona  dam.  (PL  VI.)  It  raises  the  water  of 
the  combined  Salt  and  Verde  rivers  15  feet,  or  5  feet  higher 
than  did  the  old  dam.  It  is  nearly  1300  feet  long  and,  in- 
cluding sluice  and  regulating  gates,  contains  40,000  cubic 


FIG.  50. — Plan  of  Granite  Reefs  Weir  and  Headworks,  Arizona  Canal. 

yards  of  concrete.  In  plan  it  is  straight  and  crosses  the  river 
at  right  angles  to  its  course.  The  regulating  gates  and  main 
distributing  canal  on  the  north  side  have  a  capacity  of  2000 
second-feet,  and  those  on  the  south  side  a  capacity  of  1000 
second-feet. 

The  main  body  of  the  weir  is  of  heavy  bowlders  embedded  in 
concrete.  Its  design  is  unique,  the  structure  being  divided 
horizontally  into  two  portions,  viz.,  a  massive  ogee-shaped  weir 
7  feet  6  inches  wide  at  top,  31  feet  6  inches  wide  at  bottom,  and 


204 


HEADWORKS    AND    DIVERSION    WEIRS 


Note: 

All  reinforcing 

and  of  steel     I 


18'concrete  s'o'k 


apart.  3^7 


from  26  to  30  feet  in  height,  embedded  for  a  depth  of  n  to  15 
feet  in  the  gravel  of  the  river  bottom.  This  section  is  reinforced 
near  the  crest,  down-stream  face  and  bottom  with  f-  to  f -inch  steel 
rods  laid  horizontally  12  inches  center  to  center,  and  longitudi- 
nally of  the  structure.  This  massive  weir  rests,  as  a  foundation, 

on  walls  of  reinforced  con- 
crete 3  feet  6  inches  wide 
laid  crosswise  of  the  weir 
axis  and  21°  between  cen- 
ters. These  walls  are  rein- 
forced with  i -inch  steel  rods 
set  vertically  and  spaced  2 
to  3  feet  between  centers. 
These  cross  walls  are  sunk 
9  to  19  feet  to  bed-rock  and 
form  wells  with  two  longitu- 
dinal walls  1 8  inches  thick, 
under  the  up-  and  down- 
stream faces  of  the  weir. 
The  cross  walls  extend  be- 
low the  down-stream  face  as 
a  buttress  with  i  on  2  slope. 

(Fig-  51.) 

Where  the  bed-rock  was 
of  such  a  depth  as  to  make 
it  impracticable  to  extend 
the  foundations  to  it,  three 
curtain  walls  were  built  ex- 
tending across  the  stream  in  this  section.  The  one  under  the 
upper  toe  of  the  dam  is  6  ft.  in  width  and  is  carried  down 
to  a  depth  of  about  18  ft.  below  the  elevation  of  the  apron 
below  the  dam.  The  curtain  wall  under  the  lower  toe  of  the 
dam  is  carried  to  a  depth  cf  14  ft.  below  the  surface  of  the  apron. 
Through  this  wall  were  left  openings  6  ins.  square,  placed  5  ft, 
apart  and  about  6  ft.  above  the  bottom  of  the  wall.  These 
openings  permit  the  water  that  rmy  collect  under  the  dam  to 
drain  out  under  the  apron.  The  apron  of  concrete  is  18  in.  thick 


FIG.  51. — Cross-section  of  Granite  Reefs 
Weir,  Salt  River,  Arizona. 


206  HEADWORKS   AND   DIVERSION   WEIRS 

on  a  foundation  of  placed  bowlders,  having  a  thickness  of  4^  ft. 
It  is  laid  in  squares  of  about  10  ft.  on  a  side,  between  which  a 
space  of  about  3  ins.  is  left.  This  space  permits  the  escape  of 
water  from  under  the  apron,  which  is  prevented  from  finding  an 
outlet  down  the  stream  by  the  curtain  wall  12  ft.  deep  that  is 
built  under  the  down-stream  edge  of  the  apron.  (Fig.  52.) 

189.  Other  Masonry  Weirs. — A  masonry  diversion  weir, 
which  also  serves  for  purposes  of  storage,  is  that  across  the 
Pequannock  River  near  Newark,  New  Jersey.  This  weir  (Fig. 
53)  is  built  of  rubble  masonry,  coursed  and  dressed  on  its  faces 


FIG.  52. — Granite  Reef  Weir  and  Apron,  on  Bowlder  Foundation. 

and  having  an  ashlar  capstone.  That  portion  of  the  structure 
which  acts  as  a  dam  is  38  feet  in  maximum  height,  5  feet  10  inches 
wide  on  top,  and  21  feet  wide  at  the  base.  The  remainder  of 
the  structure,  which  is  built  as  an  overfall  weir,  is  set  nearly  at 
right  angles  to  the  main  dam  and  is  curved  with  a  radius  of  640 
feet.  This  overfall  weir  is  22  feet  in  height,  its  crest  being  7  feet 
below  that  of  the  main  dam.  It  is  15  feet  in  width  at  the  base 
and  5  feet  wide  on  top,  its  lower  slope  on  the  up-stream  face  being 
vertical  for  7  feet,  above  which  it  has  an  inclination  of  3  on  i. 
The  down-stream  face  has  an  inclination  of  8  on  i  for  8  feet  below 
the  crest,  below  which  it  changes  to  about  5  on  i  for  8  feet  more, 
and  then  to  3  on  i .  The  result  is  to  give  a  clear  overfall  to  the 
bed-rock  below,  which  is  protected  by  a  trifling  depth  of  water  in 
the  river  channel,  which  acts  as  a  shallow  water-cushion.  The 
coping-stone  of  the  weir  is  made  continuous  by  means  of  dowels 
between  the  several  stones,  and  is  secured  to  the  structure  by 
anchors  let  into  the  masonry  which  hold  down  the  dowels  every 
12  feet. 


208 


HEADWORKS    AND   DIVERSION    WEIRS 


The  new  masonry  weir  recently  constructed  to  replace  the  old 
rock  and  crib  weir  at  Holyoke,  Mass.  (Fig.  37),  is  1020  feet  in 
maximum  length.  At  both  ends  are  built  wing  walls  of  masonry 
extending  to  a  height  of  12  feet  above  the  weir  crest.  The  upper 
part  of  the  down-stream  face  is  designed  on  a  parabolic  curve,  which 
is  that  of  water  falling  freely  when  flowing  4  feet  deep  over  the 
crest.  At  the  point  of  reversing  the  parabolic  curve  is  changed  to 
a  cycloidal  curve  (Fig.  54),  which  is  that  of  quickest  descent.  At 


FIG.  53. — Cross-sections  of  Newark  Dam  and  Weir. 

the  toe  is  an  up-curve  to  reduce  erosive  action.  The  slope  of 
the  up-stream  face  is  i  on  5,  which  is  stepped  off  every  5  feet. 
The  materials  of  construction  are  rubble  masonry  with  dressed 
stone  cap  and  facing  and  concrete  toe  and  footing.  Each  stone 
of  the  first  eight  courses  is  tied  with  galvanized  dogs  or  dowels. 

190.  Diversion  Dams. — There  are  several  structures  of  con- 
siderable magnitude  which,  from  the  functions  they  perform, 
should  be  classed  as  diversion  weirs  rather  than  storage  dams. 
Prominent  among  these  are  the  Betwa  dam  in  India  and  the  Fol- 
som,  Austin,  and  La  Grange  dams  in  the  United  States  (Arts. 
355  to  35&)'  The  two  latter  were  built  solely  for  purposes  of 
diversion,  while  the  former  serves  to  store  as  well  as  to  divert 


RIVER-TRAINING    WORKS 


20Q 


water.  These  works,  however,  are  ot  such  magnitude  that  the 
principles  involved  in  their  design  and  construction  are  essen- 
tially those  employed  in  designing  masonry  dams  for  water  stor- 
age, and  for  this  reason  they  are  described  among  masonry  dams. 
191.  River- training  Works. — In  connection  with  all  irri- 
gation works  heading  in  lowlands  where  the  slopes  of  the  stream- 


El.   100.2' 


80'— 


h—H 


--(El.  7T 


FIG.  54. — Cross-section  of  New  Holvoke  Weir,  Mass. 

beds  are  slight  and  their  banks  of  sand,  silt,  or  other  easily  eroded 
material,  river-training  or  improvement  works  must  be  con- 
structed in  order  to  maintain  the  stream  in  the  channel  which 
will  cause  it  to  do  the  least  injury  to  the  diversion  works.  During 
periods  of  high  flood  such  rivers  erode  their  banks  and  may  change 
their  channels  to  such  extent  as  to  leave  the  head  or  diversion 
works  dry  and  high  or  to  undermine  and  destroy  them,  unless  the 
river  is  so  trained  as  to  secure  for  it  a  permanent  channel  for 
some  distance  above  and  below  the  diversion  works. 

Such  training-works  have  been  extensively  constructed  at  the 
heads  of  many  of  the  great  Indian  canals  which  head  in  lowlands 
or  deltas.  The  works  for  the  protection  of  the  Narora  weir  of 


210  HEADWORKS    AND    DIVERSION    WEIRS 

the  Lower  Ganges  canal,  India,  extends  4  miles  above  and  15 
miles  below  the  canal  head.  They  consist  of  a  long  earth  em- 
bankment or  levee  from  which  shorter  embankments  or  groins 
project  at  right  angles  to  the  course  of  the  stream.  The  groins 
are  10  feet  wide  on  top  with  slopes  of  i  on  2  and  are  i  to  2  miles 
in  length.  The  end  150  feet,  or  the  nose,  has  a  5o-foot  spur 
pointing  up-stream  at  50  feet  from  the  end  of  the  groin.  The 
entire  nose  is  paved  with  heavy  dry -laid  rubble  to  a  depth  of  2  to 
3  feet.  Similar  groins  are  sometimes  necessary  in  weirs  built 
across  broad,  shallow  river  channels.  These  project  at  right 
angles  to  the  weir  and  parallel  to  the  river's  course  to  train  the 
latter  straight  across  the  weir.  Otherwise  the  water  might  be 
deflected  away  from  the  headgates,  or  towards  them  so  as  to 
injure  them. 

A  good  example  of  such  works  is  on  the  Yuma  project  on  the 
Colorado  River  (Art.  194).  Here  the  river  floods  are  restrained 
by  earth  dikes  or  levees  similar  to  those  so  successfully  em- 
ployed on  the  Mississippi  River.  These  levees  have  slopes  of  i 
on  3  on  the  water  side  and  i  on  2^  on  the  land  side.  They  are 
8  feet  wide  on  top  and  extend  5  feet  above  the  highest  flood  mark. 
The  most  magnificent  examples  of  river-training  works  are  to  be 
found  on  the  Mississippi  and  its  branches,  where  it  has  been 
found  necessary  to  guide  and  maintain  their  channels  with  a  view 
to  the  improvement  of  navigation.  These  works  consist,  accord- 
ing to  circumstances,  of  walls  or  embankments  parallel  to  the 
channels  of  the  streams  so  as  to  give  them  a  uniform  waterway, 
or  of  jetties  run  out  at  right  angles  to  the  banks  so  as  to  direct 
their  flow,  and  of  combinations  of  embankments,  jetties  and 
groines. 


CHAPTER  XI 

SLUICEWAYS,    REGULATORS,    AND    ESCAPES 

192.  Sluiceways. — Sluiceways,  scouring-  or  undcrsluices,  are 
placed  in  the  bottom  of  nearly  every  well-constructed  weir  or  dam, 
at  the  end  immediately  adjacent  to  the  regulator  head.  Their 
object  is  to  remove,  by  the  erosive  action  of  the  water,  any  sedi- 
ment which  may  be  deposited  in  front  of  the  regulator.  If  the 
flow  in  the  stream  is  sufficiently  great,  these  sluices  are  kept  con- 
stantly open  and  thus  perform  their  functions  by  keeping  the 
water  in  motion  past  the  regulating  head  and  thus  preventing  the 
silt  from  settling.  If  sufficient  water  cannot  be  spared  to  leave 
the  sluices  constantly  open,  they  are  opened  during  flood  and 
high  waters,  and  by  creating  a  swift  current  are  effectual  in  re- 
moving silt  which  has  been  deposited  at  other  times. 

The  scouring  effect  of  sluices  constructed  in  the  body  of  the 
weir  is  produced  by  two  classes  of  contrivances;  namely,  by  open 
sluiceways  and  by  undersluices.  The  open  scouring  sluice  is 
practically  identical  with  the  open  weir,  as  the  latter  consists  of 
sluiceways  carried  across  the  entire  width  of  the  channel.  Where 
the  weir  forms  a  solid  barrier  to  the  channel  and  is  only  open  for 
a  short  portion  of  its  length  adjacent  to  the  canal  head,  the  latter 
is  spoken  of  as  a  sluiceway.  The  waterway  of  a  scouring  sluice 
is  open  for  the  entire  height  of  the  weir  from  its  crest  to  the  bed 
of  the  stream. 

Undersluices  are  more  generally  constructed  where  the  weir 
is  of  considerable  height  and  the  amount  of  silt  carried  in  suspen- 
sion is  relatively  small.  In  these  the  opening  does  not  extend  as 
high  as  the  crest  of  the  weir,  nor  does  the  sill  of  the  sluiceway 
necessarily  reach  to  the  level  of  the  stream-bed.  It  is  chiefly 
essential  that  its  sill  shall  be  as  low  as  the  sill  of  the  regulator  head. 
Undersluices  are  more  commonly  employed  in  the  higher  struc- 

211 


212  SLUICEWAYS,    REGULATORS,    AND    ESCAPES 

tures,  such  as  weirs  and  dams  which  close  storage  reservoirs 
(Articles  376  and  377). 

Sluiceways  are  practically  open  portions  of  the  weir  and  con- 
sist of  a  foundation,  floorway,  and  superstructure.  The  floor 
must  be  deep  and  well-constructed  and  carried  for  a  short  dis- 
tance up-stream  from  the  weir  axis  and  for  a  considerable 
distance  below  it.  On  it  are  built  piers  grooved  for  the  re- 
ception of  planks  or  gates,  so  that  the  sluiceway  may  be  closed 
or  opened  at  will. 

193.  Examples  of  Sluiceways. — At  the  head  of  the  Monte 
Vista  canal,  Colorado,  are  sluiceways  of  wood.  The  weir  is 
built  across  the  gravel  bed  of  the  Rio  Grande,  and  is  founded  on 
piles  sunk  to  a  depth  of  10  feet.  The  weir  terminates  at  the  end 
adjacent  to  the  regulator  head  in  five  scouring  sluices.  These  are 
founded  on  piles,  and  the  stream-bed  beneath  is  floored  with 
planking  to  form  an  apron  to  protect  it  against  erosion.  The 
openings  are  separated  by  upright  posts  of  wood  reaching  to  the 
crest  of  the  weir,  and  can  be  closed  by  flashboards  dropped  be- 
tween grooves. 

An  excellent  example  of  masonry  scouring  sluice  is  in  the 
weir  at  the  head  of  the  Agra  canal  in  India.  In  the  end  of  the 
weir  adjacent  to  the  canal  head  are  a  set  of  16  openings  having 
a  clear  sluiceway  of  138  feet.  These  openings  are  each  6  feet 
in  width  between  the  upright  piers  separating  them  and  are  10 
feet  in  height,  surmounted  by  a  masonry  superstructure  or  bridge 
the  height  of  which  is  19  feet  above  the  stream-bed.  The  object 
of  this  bridge  is  to  give  a  platform  from  which  to  operate  the 
sluice  gates,  which  are  of  wood,  well  braced  and  fastened  with 
iron,  and  slide  vertically  between  masonry  piers  each  2\  feet  in 
thickness.  They  are  raised  by  means  of  a  winch  which  is  oper- 
ated from  above,  travels  on  a  hand  car  on  rails  so  that  it  can 
be  placed  at  will  above  any  gate.  The  floor,  which  is  flush  with 
the  stream-bed  and  on  a  level  with  the  sill  of  the  regulator  head, 
is  12  feet  in  width  parallel  to  the  stream  channel  and  extends  8 
feet  up-stream  and  41  feet  down-stream  from  the  line  of  the  piers. 
When  these  gates  are  open  all  the  heavy  silt-laden  waters  are 
carried  through  the  sluices,  and  when  closed  and  then  suddenly 


2I3 


Figures  without  dimension   lines 
are  elevation*. 


Elevations  refer  to  St»  Icrel 


214  SLUICEWAYS,    REGULATORS,    AND    ESCAPES 

opened  the  scour  produced  by  the  rush  of  water  is  effective  in 
removing  the  silt  from  in  front  of  the  canal  head. 

194.  Yuma  Project  and  Sluiceways,  Laguna  Weir. — The 
Reclamation  Service  has  constructed  a  project  near  Yuma, 
Arizona,  for  the  irrigation  of  land  on  both  sides  of  the  Colorado 
River  which  contemplates  the  permanent  reclamation  of  nearly 
97,000  acres  by  a  combination  of  irrigation  levee  and  drainage 
works.  The  deposition  of  silt  of  the  Colorado  River  is  one  of  the 
most  difficult  features  and  greatly  influenced  the  type  of  head- 
works  and  the  design  of  scouring  sluices  to  remove  silt  at  the  canal 
head.  The  occasional  overflow  of  the  Colorado  River  made 
necessary  the  leveeing  of  the  entire  tract.  Most  of  the  silt  is  car- 
ried near  the  bottom  of  the  river,  the  surface-water  being  rela- 
tively free  from  sediment.  Water  is,  therefore,  taken  into  the 
canals  by  a  skimming  process  over  a  long  row  of  flashboards, 
the  canal  thus  being  filled  by  drawing  but  i  foot  in  depth  of 
water  from  the  surface  of  the  river.  (Art.  195.)  The  first  3,000 
feet  of  the  canal  on  each  side  of  the  river  are  constructed  of  such 
size  that  the  movement  of  the  water  through  it  is  slower  than  i 
foot  per  second,  thus  creating  in  that  portion  of  the  canals  a 
settling  basin. 

The  grade  of  the  river  at  the  weir  site  is  about  i  foot  to  the 
mile,  so  that  a  weir  10  feet  high  creates  a  settling-basin  of  rel- 
atively quiet  water  for  approximately  10  miles  in  length  above 
it.  At  each  side  of  the  weir  and  excavated  to  the  depth  of  low 
water  in  the  river  is  a  sluiceway  200  feet  wide.  (Fig.  55.)  The 
sluiceways  are  closed  by  large  gates  operated  by  hydraulic 
machinery.  The  area  of  these  sluiceways  is  so  great  that  the 
water  movement  toward  the  canal  will  be  sufficiently  slow  to 
permit  most  of  the  sediment  to  be  deposited  before  reaching  the 
canal  intake.  When  a  sufficient  accumulation  has  occurred  the 
sluice-gates  will  be  opened  and  the  capacity  of  each  sluiceway 
being  approximately  20,000  second-feet,  the  rush  of  this  volume 
of  water  is  expected  to  carry  out  the  sediment  above  the  canal  in- 
take. The  ordinary  low-water  flow  of  the  Colorado  River  is  from 
3500  to  4000  second-feet;  the  capacity  of  each  sluiceway  is, 
therefore,  about  five  times  this  volume.  At  the  lower  end  of  the 


YUMA   PROJECT   AND    SLUICEWAYS 


215 


settling-basins  gates  are  arranged  to  discharge  into  the  river  so 
that  the  water  can  be  drawn  down  to  the  level  of  the  stream,  and  a 
grade  of  n  feet  in  3000  feet  is  thus  obtained  to  give  swift  cur- 
rent for  the  scouring.  At  the  lower  end  of  the  settling-basins 
the  canal  begins. 

The  weir  and  headworks  are  of  rock,  concrete,  or  steel,  with 
the  exception  of  the  sheet-piling,  which  is  driven  entirely  below 
the  water-level  and  is  thus  not  subject  to  decay.  The  canals  are 
designed  so  that  water  will  flow  at  a  higher  velocity  through  them 


riprapped  with  loose  rtone 

—  . 

V    Top  of  Embankment  Elev.  1325 


PLAN 

FIG.  56. — Plan  of  Headworks,  Granite  Reef  Weir,  Salt  River,  Arizona. 

than  in  the  settling-basins,  the  effect  being  to  prevent  the  deposi- 
tion of  sediment  in  them. 

At  either  extremity  of  the  Granite  Reefs  weir  of  the  Salt  River 
project,  Arizona,  of  the  United  States  Reclamation  Service,  and 
in  front  of  the  intake  basins  to  the  canal  regulators,  are  sluice- 
ways designed  to  carry  off  much  of  the  heavier  silt-laden  water 
of  flood  rises  and  thus  prevent  the  deposition  of  silt  at  the  canal 
entrances.  They  are  also  designed  to  scour  out  such  sediment 
as  may  accumulate  at  these  points.  The  north  sluiceway  con- 


216 


SLUICE   GATES,    LACUNA   WEIR 


2I7 


sists  of  four  openings  each  1 5  feet  wide  in  the  clear.  A  concrete 
wall  extends  200  feet  up-stream  from  the  pier  next  the  main  weir 
with  a  view  of  directing  the  flow  of  water  into  the  basin  at  the 
head-works.  (Fig.  56.)  Each  opening  is  closed  with  metal 
gates  9  feet  high  between  piers  5  feet  7  inches  thick  and  37  feet  in 
length  parallel  to  the  stream.  The  entire  structure  is  of  concrete 
masonry  (Fig.  60),  abutting  on  either  side  against  similar  mas- 
onry in  the  weir  and  regulator.  The  piers  rise  to  a  height  of 
33  feet  9  inches  or  15  feet  8  inches  above  the  weir  crest.  A  con- 
crete floor  several  feet  in  thickness  extends  for  some  distance 
above  and  below  the  sluiceway. 

195.  Sluice   Gates,   Laguna   Weir.— These  gates   are   set    in 


FIG.   58. — Half  Plan,  Sluice  Gate,  Laguna  Weir,  Colorado  River,  California. 

concrete  masonry  piers  8  feet  wide  and  48  feet  long,  by  40  feet 
9  inches  in  height  above  the  gate  scats. 

Each  opening  has  a  clear  waterway  width  of  33  feet  4  inches. 
A  distance  of  8  ft.  above  the  service  gate  seats  is  a  set  of  gate  seats 
for  emergency  purposes.  But  one  emergency  gate  is  provided  for 
the  three  openings,  this  gate  being  transferred  from  one  opening 
to  another  as  necessity  demands.  There  is  a  girder  bridge  with- 
out a  floor  over  the  tops  of  the  piers  and  abutments  above  the 
position  of  the  emergency  gate  seats.  This  bridge  is  provided 
with  a  track  for  a  car  on  which  the  operating  machinery  for  the 
emergency  gate  is  located  and  which  is  used  in  transferring  this 
gate  from  one  set  of  gate  seats  to  another  (Fig.  57).  A  similar 
bridge,  with  a  floor,  is  placed  above  the  service  gate  seats  for  the 
operating  machinery  for  the  service  gates.  The  bodies  of  the 
gates  (Fig.  58)  are  constructed  throughout  of  suitable  plates  and 


2l8  SLUICEWAYS,    REGULATORS,    AND    ESCAPES 

angles,  with  riveted  connections,  and  are  17  ft.  n£  ins.  high  and 
34  ft.  gi  ins.  wide.  The  thickness  of  the  plates  and  the  sizes  of 
the  angles  throughout  are  proportioned  to  the  stresses  upon  them. 
The  water  pressure  is  taken  directly  by  a  skin  plate  on  the  up- 
stream face  of  the  gate  and  transferred  laterally  to  the  piers  at 
the  side  of  the  gate  by  means  of  four  horizontal  riveted  girders. 
Each  girder  has  a  maximum  depth  at  the  center  of  42  ins.,  a 
minimum  depth  at  the  ends  of  27  ins., 'and  is  composed  of  flange 
angles  and  a  web  plate,  reinforced  with  angle  stiffeners  at  intervals 
of  about  2\  ft.  The  three  lower  girders  are  equally  spaced  at  a 
distance  of  about  5  ft.,  while  the  distance  between  the  two  upper 
ones  is  about  7^  ft.  The  four  girders  are  interbraced  by  means 
of  five  cross  girders,  likewise  composed  of  angles  and  plates.  To 
prevent  lateral  motion  of  the  gates  there  are  placed  on  the  sides 
of  each  gate,  at  the  four  corners,  cast-iron  rollers  having  an  ap- 
proximate length  and  diameter  of  6  ins.,  which  have  rolling  con- 
tact with  the  gate  frames.  On  the  backs  of  the  gates,  at  the  ends 
of  the  girders,  are  attached  cast-steel  strips,  having  finished  sur- 
faces 6^  ins.  wide  for  transferring  the  water  pressure  through  the 
roller  trains  to  the  roller  tracks  on  the  gate  frames.  The  lower 
edges  of  the  skin  plate  and  end  web  plates  are  finished  to  a  true 
surface  to  form  a  water-tight  seat  on  the  gate  sill.  Attached  to 
the  front  of  each  gate,  by  means  of  angles,  adjacent  to  the  piers 
and  abutments  are  3x3-111.  needles  of  Oregon  fir.  These 
strips  of  wood  are  so  placed  as  to  form  snug  contact  with  an 
exterior  flange  of  the  gate  frame  castings,  and  thereby  prevent 
seepage  around  the  ends  of  the  gates. 

The  gate  sills  are  composed  of  wrought-iron  plates  fastened 
with  lag  screws  to  I2xi2-in.  white-oak  timbers  anchored  to  the 
rock  floor  of  the  sluiceways.  Each  roller  train  contains  26  cast- 
iron  rollers,  6  ins.  in  diameter  and  5  11-16  ins.  in  length,  fitted 
between  two  |x6-in.  wrought-iron  plates,  19  ft.  10  ins.  long. 
The  rollers  have  bronze  bushings  and  revolve  about  ij-in.  steel 
pins  that  pass  through  both  the  bronze  bushings  and  the  wrought 
iron  plates.  The  ends  of  the  roller  racks  contain  pulleys  around 
which  J-in.  crane  chains  pass.  One  end  of  each  of  these  chains 
passes  over  a  sheave  located  on  the  operating  bridge,  thence  to 


SLUICE    GATE,    GRANITE    REEF    WEIR 


2IQ 


an  attachment  on  a  counterweight  box.  The  other  end  of  the 
chains  is  secured  to  small  cast-iron  drums,  also  located  on  the 
operating  bridges.  By  means  of  this  arrangement,  it  is  possible 
to  raise  the  roller  trains  to  the  full  height  of  the  position  of  the 
gates  by  hand  operation  of  the  cast-iron  drums. 

Each  counterweight  box  weighs  6500  Ibs.,  and,  including  the 


weights,  a  total  of  48,500  Ibs.  are  counterpoised  against  the  weight 
of  the  gate.     The  gates  are  electrically  operated. 

196.  Sluice  Gate,  Granite  Reef  Weir. — The  method  of  opera- 
tion of  these  sluice  gates  is  unique,  the  design  being  such  as  to 


220 


SLUICEWAYS,    REGULATORS,    AND   ESCAPES 


give  clear  overhead  passage  to  the  great  floods  which  may  assail 
this  structure.  There  are  four  clear  openings  in  the  north  sluice- 
way (Art.  194),  each  15  feet  wide  by  20  feet  high  and  closed  with 
lifting  steel  gates  9  feet  high  (Fig.  59).  The  separating  piers 
are  each  5  ft.  7  in.  in  thickness,  of  concrete,  and  founded  on  a 
mass  of  concrete  10  feet  in  thickness  resting  on  solid  rock.  In 
this  foundation  mass  is  a  tunnel  in  which  run  eight  plow  steel 
ropes  of  ij  in.  thickness  which  pass  up  shafts  in  the  piers  to  chain 
wheels  31  in.  in  diameter.  These  chains  are  operated  by  an 


FIG.  60. — Rear  of  Sluice  Gate  before  being  Concreted.     Granite  Reef  Weir, 
Arizona  Canal. 

hydraulic  cylinder  actuated  by  electric  motor  and  pump  placed 
on  the  abutment.  The  arrangement  is  such  that  all  four  gates 
can  be  raised  or  lowered  at  once  from  this  station. 

The  sluice-gate  has  at  the  up-stream  face  a  cast-iron  curved 
shell  f-in.  thick,  made  in  halves  and  riveted  together  in  the  field. 
The  gate  is  filled  with  concrete,  giving  it  a  total  weight  of  about 
30,000  Ibs.  (Fig.  60.)  Each  sluice-gate  is  suspended  by  two 
chains  of  i  J-in.  metal,  which  are  carried  first  over  31 -in.  diameter 
pocketed  chain  wheels,  then  down  through  the  pier  or  abutment 


FALLING    SLUICE-GATES  221 

into  a  tunnel,  then  under  21 -in.  diameter  chain  wheels.  The 
chains  connect  with  the  two  ends  of  a  i  J-in.  diameter  steel  rope 
that  is  laid  around  a  lug  on  the  periphery  of  a  steel  drum  of 
7  ft.  radius.  There  is  one  lug  for  each  sluice-gate. 

197.  Falling  Sluice-gates. — Various  devices  have  been   em- 
ployed  whereby  the  gates  closing  sluiceways   may  be  opened 
rapidly  and  under  the  greatest  pressure  of  water  which  may  be 
brought  against  them  by  sudden  flood  rises.     In  nearly  all  scour- 
ing sluices  the  gates  are  operated  from  a  superstructure  above 
the  level  of  the  highest  flood.     This  form  of  construction  is  ex- 
pensive and  interferes  with  the  free  flow  of  water  by  stopping  and 
perhaps  choking  the  sluices  with  floating  brushwood  and  logs. 
To  remedy  this  and  obtain  the  largest  percentage  of  free  space 
between  the  piers  for  the  passage  of  flood  waters,  some  modern 
Indian  works  have  been  given  much  larger  openings  between 
piers,  and  the  gates  are  so  operated  that  no  superstructure  is 
necessary  above  the  level  of  the  weir  crest.     As  a  result  the  floods 
may  pass  with  little  obstruction  over  as  well  as  through  the  weirs. 
Such  structures  as  these  are  of  necessity  strongly  constructed  and 
are  made  capable  of  quick  operation.     Two  excellent  examples 
of  this  class  of  structure  are  furnished  by  the  shutters  in  the  Maha- 
nuddy  weir  at  the  head  of  the  Orissa  canals  and  those  of  the 
Dchree  weir  at  the  head  of  the  Soane  canals  in  India. 

198.  Bear-trap    Movable    Sluice-gates. — One    of    the    most 
satisfactory  rapidly  operated  movable  sluice-gates  or  shutters  is 
the  American  type  of  bear-trap  gate  as  developed  on  the  Great 
Kanawha  River,  W.  Va.,  by  the  Engineer  Corps  of  the  Army. 
This  gate  is  almost   automatic   in  operation.     When  raised   it 
forms  an  obstruction  or  weir  across  the  entire  width  of  the  channel, 
and  when  lowered  it  is  either  lifted  above  the  water  surface  or 
dropped  against  the  bed  of  the  stream  so  as  to  offer  no  obstruction 
to  its  free  flow.     The  Chanoine  modification  of  the  original  bear- 
trap  weir  shutter  is  illustrated  in  Fig.  6 1,  which  is  self-explanatory. 

The  essential  features  of  the  old  bear-trap  gate  are  two  leaves 
built  across  the  sluiceway  and  fastened  by  horizontal  hinges  at 
the  bottom.  When  the  sluiceway  is  open  the  leaves  lie  in  a  hori- 
zontal position,  the  up-stream  leaf  overlapping  the  other  for  a 


222 


SLUICEWAYS,    REGULATORS,    AND    ESCAPES 


portion  of  its  length.  When  the  sluiceway  is  closed  the  two  leaves 
form  a  triangle,  of  which  the  bottom  of  the  sluiceway  is  one  side 
and  the  leaves  the  other  two,  the  apices  being  at  the  two  hinges 
and  where  the  leaves  abut  against  each  other.  The  space  within 
the  triangle  is  a  chamber  which  may  be  filled  by  inlet  pipes  closed 
by  means  of  valves  under  the  control  of  the  operator  of  the  gate. 
To  raise  the  gate  the  outlet  from  the  chamber  below  is  closed  and 
the  inlet  opened,  when  the  water  fills  the  chamber  and  presses 
the  lower  surface  of  the  leaves.  As  the  water  has  also  access  to 
the  upper  surface  of  the  upper  leaf,  the  pressure  from  below  upon 
it  is  neutralized;  on  the  lower  leaf  there  is  no  counter  pressure, 


FIG.  61. — Chanoine  Movable  Shutter,  Raised,  Lowered,  and  Closed. 

and  therefore  the  pressure  from  below  tends  to  raise  it,  and  also 
the  upper  leaf  which  rests  upon  it.  This  is  done  in  a  properly 
proportioned  structure,  and  the  gate  is  carried  to  a  height  limited 
by  the  dimensions  of  the  leaves.  To  lower  the  gates  the  water 
from  above  is  cut  off,  the  outlet  valves  are  opened,  and  the  chamber 
emptied.  The  pressure  of  the  water  is  thus  thrown  on  the  upper 
leaf,  and  forces  it  back  into  a  horizontal  position  against  the  bed 
of  the  sluiceway. 

This  form  of  gate  has  been  found  difficult  of  operation,  owing 
chiefly  to  the  difficulties  of  properly  proportioning  the  angles  and 
lengths  of  the  leaves.  Improvements  have  resulted  in  the  ad- 
dition of  a  leaf,  or,  more  correctly,  in  practically  dividing  the  upper 
leaf  into  two  parts  or  joints  (Fig.  62),  so  that  as  the  sluice-gate  is 
lowered  the  upper  leaf  which  is  jointed  near  its  center  folds  in- 


MAHANUDDY    SLUICE    SHUTTERS 


223 


ward,  that  is,  into  the  chamber,  while  the  upper  and  lower  leaves 
are  hinged  together  at  the  top.  This  is  practically  the  Parker 
gate,  in  which  have  been  eliminated  nearly  all  the  difficulties  of 
the  old  bear-trap,  as  there  is  no  overlapping  at  the  apex,  while  the 
height  obtainable  for  the  same  length  of  sluice  is  over  twice  as 
great;  there  is  no  sliding  friction,  and  the  gate  cannot  be  brought 
to  a  sudden  stop  when  it  approaches  its  full  height,  but  comes  to  a 
rest  gently.  The  conditions  which  give  the  most  satisfactory 
length  of  leaf  for  the  Parker  gate  are,  according  to  Lieut.  H.  M. 
Chittenden,  U.  S.  A.,  lower  leaf  plus  lower  section  of  upper  leaf 
minus  upper  section  of  upper  leaf  equals  the  base,  and  that  when 


HIS  3E 


HIN 


HINGE: 


LET  OUTLET ^ 

FIG.  62. — Bear-trap  Gat:,  Parker  Modification. 

raised  to  full  height  they  shall  not  rise  above  a  curve  corresponding 
to  the  particular  condition  of  back-water.  The  proportions  as 
shown  in  Fig.  62,  however,  practically  fill  all  conditions  essential 
to  successful  operation. 

199.  Mahanuddy  Sluice  Shutters. — These  shutters  are  de- 
signed somewhat  after  the  plan  adopted  on  some  of  the  older 
weirs  across  the  river  Seine  in  France.  Each  bay  of  the  sluiceway 
is  closed  by  a  double  row  of  timber  shutters  fastened  by  wrought - 
iron  bolts  and  hinges  to  a  heavy  beam  of  timber  embedded  in  the 
masonry  floor  of  the  sluice  (Fig.  63).  These  shutters  are  arranged 
in  pairs,  the  lower  shutters  being  9  feet  in  height  above  the  floor, 
and  the  upper  shutters  7^  feet  in  height.  Each  bay  is  separated 
from  the  next  by  a  stone  pier  5  feet  thick,  to  which  the  gearing  for 


224  SLUICEWAYS,    REGULATORS,    AND    ESCAPES 

working  them  is  attached.  During  the  floods  the  upper  row  of 
shutters,  which  fall  forward  up-stream,  are  held  to  the  floor  of  the 
weir  in  an  almost  horizontal  position  by  means  of  iron  clutches. 
The  rear  or  lower  row  of  shutters  which  fall  down-stream  are  kept 
in  a  horizontal  position  by  the  rush  of  water  over  them.  In  order 
that  the  down-stream  row  of  shutters  may  be  retained  in  position 
and  act  as  dams  when  raised,  they  are  provided  with  strong 
wrought-iron  struts  attached  to  their  lower  sides.  In  order  to  lift 
the  lower  set  of  shutters  when  the  water  is  resting  on  top  of  them 
the  up-stream  set  of  shutters  are  first  raised,  this  operation  being 
aided  by  the  upward  pressure  of  water  from  beneath,  and  they  are 
retained  in  a  vertical  position  by  means  of  chains  guyed  to  the 


FIG.  63. — Cross-section  of  Mahanuddy  Automatic  Shutters,  India. 

piers  above  them.  Relieved  of  the  water  pressure  by  this  upper 
set  of  shutters  it  then  becomes  possible  to  raise  the  lower  set  by 
means  of  a  hand  windlass,  after  which  the  upper  set  are  lowered 
again  into  their  original  position  and  the  weir  is  ready  to  withstand 
the  next  flood,  as  the  lower  set  can  then  be  instantly  dropped  by 
merely  removing  the  bolts  which  support  them. 

200.  Soane  Falling  Sluice-gates. — The  shutters  of  the  Maha- 
nuddy weir  have  never  been  successfully  operated  against  a 
greater  head  than  6J  feet,  and  the  jar  produced  by  opening  the 
upper  gates  and  by  the  fall  of  the  lower  gates  has  always  been 
violent.  To  diminish  this  jarring  action  and  to  obtain  a  more 
easy  and  successful  operation  in  the  shutters  of  the  Soane  weir, 
a  new  design  was  devised,  and  it  furnishes  what  is  probably  the 
best  example  of  self-acting  sluice-gate  which  has  yet  been  con- 
structed. 


SOANE    FALLING    SLUICE-GATES 


225 


PLATE  XI. — Falling  Sluice-gate.     Soane  Canal,  India. 


226  SLUICEWAYS,    REGULATORS,    AND   ESCAPES 

The  crest  of  the  Soane  weir  is  gj  feet  above  the  river-bed,  and 
the  grates  by  which  the  sluice-ways  are  closed  are  each  20  feet  in 
length  and  gj  feet  high.  They  are  separated  by  masonry  piers 
6^  feet  thick  by  32  feet  in  length.  The  floor  of  these  sluices  is 
very  substantial  and  is  90  feet  in  length,  parallel  to  the  river  chan- 
nel. As  the  velocity  of  the  current  through  them  may  be  as  high 
as  17 \  feet  per  second,  it  was  found  necessary  in  order  to  with- 
stand its  erosive  action  to  found  the  flooring  on  wells  or  blocks 
upon  which  an  ashlar  pavement  15  inches  in  thickness  has  been 
built  up.  The  gates  are  constructed  of  wood,  well  braced  and 
set  in  pairs  in  each  opening  (PI.  XI).  A  low  masonry  wall  12 
inches  high  has  been  built  up  on  the  down-stream  side  of  the  floor- 
ing in  each  alternate  bay,  thus  giving  a  water-cushion  of  that 
depth  on  which  the  lower  gate  falls,  relieving  the  piers  of  a  por- 
tion of  the  shock.  The  upper  gate  falls  up-stream,  being  hinged 
to  the  floor  at  its  bottom  and  held  upright  by  a  series  of  six  struts. 
These  are  hollow  iron  cylinders  with  small  vent-holes,  and  in  them 
pistons  work  in  such  manner  that  when  the  gate  is  raised  by  the 
pressure  of  water  beneath  it  the  impact  against  the  struts  is 
relieved  by  the  pistons  plunging  into  the  cylinders,  from  which  the 
water  is  slowly  forced  through  the  vent-holes.  The  lower  gates 
fall  down-stream  and  are  supported  by  four  iron  rods  hinged  to 
their  upper  faces  below  the  center  of  pressure,  and  when  in  posi- 
tion are  held  upright  by  chains  attached  to  the  piers  above.  If 
both  gates  are  open  and  it  is  desired  to  close  the  lower  one  so  as 
to  cause  it  to  dam  up  the  water,  it  is  first  relieved  by  pushing 
aside  the  catch  which  attaches  the  uppej  gate  to  the  floor  when 
this  is  raised  a  little  by  means  of  a  hand  lever,  after  which  the 
force  of  the  water  brings  it  up  slowly  for  a  short  distance  and 
then  with  a  jar  against  its  hydraulic  struts  or  rams.  The  pres- 
sure is  now  relieved  from  the  lower  gates,  which  can  be  raised  by 
hand  levers  and  chained  in  an  upright  position  to  the  piers.  The 
upper  gate  is  again  lowered,  now  falling  chiefly  by  its  own  weight 
through  the  water,  and  is  fastened  down  by  clutches.  The  lower 
gate,  which  now  acts  as  the  dam,  is  prepared  to  be  released  at  a 
moment's  notice. 

201.  Automatic    Wasteway    Gate. — On    the    Belle    Fourche 


RELATIONS   OF   WEIRS   TO   REGULATORS 


227 


canal,  South  Dakota,  the  Reclamation  Service  has  designed  some 
small  automatic  iron  waste  gates.  The  wasteway  section  is  5  feet 
wide  and  the  ribbed  iron  gate  closing  it  is  5  feet  square.  It  is 
supported  by  an  iron  strut  which  half  rolls  on  a  cogged  rack. 
This  gate  is  balanced  for  a  head  of  4.95  feet,  when  it  opens 
by  swinging  upward  through  an  arc  of  45  degrees.  For  a  head 
of  4.5  feet  it  closes  automatically.  (Fig.  64.) 

202.  Relation  of  Weirs  to  Regulators. — A  diversion  weir 
retards  the  flow  of  the  stream  and  raises  the  level  of  the  water  to 
a  sufficient  height  to  enable  it  to  enter  the  canal  head.  The  reg- 
ulator is  the  controlling  valve  which  admits  this  water  to  the  canal 


Balancing  Head  4.95  Gate  Open 
Balancing  Head  J£&teJGto^i 


In'n*  WaJj 

FIG.  64. — Automatic  Wasteway  Gate,  Belle  Fourche  Canal,  South  Dakota. 

if  required,  or  prevents  its  entrance  and  causes  it  to  pass  on  down 
the  stream  over  or  through  the  weir.  The  weir  is  the  boiler  which 
generates  the  power;  the  regulator  is  the  throttle-valve  which 
controls  its  entrance  to  the  machinery.  The  regulator  should 
be  so  located  with  relation  to  the  weir  that  the  water  held  up  by 
the  latter  will  pass  at  once  and  with  the  least  loss  of  head  through 
the  former  and  into  the  canal.  This  is  effected  most  successfully 
by  placing  the  canal  head  immediately  adjacent  to  the  weir  and 
building  it  in  unison  with  and  as  part  of  the  structure.  The  weir 
should  not  be  so  aligned  as  to  cross  the  river  diagonally  at  an  angle 
inclined  either  to  or  from  the  regulator  head.  In  the  former  case 


228 


SLUICEWAYS,    REGULATORS,    AND    ESCAPES 


it  tends  to  force  the  water  against  the  regulator,  creating  an 
unnecessary  scour  at  that  point  and  producing  an  undue  pressure 
or  strain  upon  the  head.  It  should  not  incline  away  from  the 
regulator,  as  the  reverse  effect  would  be  produced  and  it  would 
cease  to  perform  its  function  of  directing  the  water  into  the  canal. 
The  best  alignment  for  the  weir  with  relation  to  the  regulator  is 
to  have  it  cross  the  stream  at  right  angles  to  the  line  of  the  latter. 


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FIG.  65.  —  Plan  of  Headworks,  Ganges  Canal,  India. 

This  gives  a  clear  even  scour  past  the  regulating  gates  and  keeps 
them  clear  of  silt,  at  the  same  time  furnishing  the  required  amount 
of  water. 

The  regulator  should  not  be  located  at  a  distance  from  the  end 
of  the  weir;  otherwise  a  dead  water  is  created  between  the  weir 
and  the  regulator  in  which  deposits  of  silt  occur,  blocking  the 
entrance  to  the  canal  and  diminishing  the  volume  available  for 
its  supply.  An  example  of  such  faulty  location  is  that  illustrated 


GRANITE   REEF   REGULATOR 


229 


in  Fig.  65,  showing  the  head  of  the  Ganges  canal,  where  the 
front  of  the  regulator  is  not  at  right  angles  to  the  weir  and  is  at 
a  short  distance  from  it,  resulting  in  the  formation  of  a  sand-bar 
at  its  entrance.  A  better  arrangement  would  be  a  regulator  built 
as  indicated  by  the  dotted  outlines,  with  its  face  at  right  angles 
to  the  line  of  the  weir. 

An  illustration  of  faulty  relation  of  weir  to  regulator  is  shown 
in  Fig.  66  in  the  old  Arizona  canal  hcadworks.  The  weir  was 
built  at  an  angle  to  the  channel  of  the  stream,  and  the  regulator 
head  was  built  at  an  angle  both  to  the  stream  channel  and  to  the 


FIG.  66. — Old  Arizona  Canal.     Plan  of  Headworks. 

weir,  the  result  being  to  force  a  great  pressure  of  water  against 
the  regulating  gates,  which  seriously  damaged  them,  while  the 
deposition  of  sediment  between  the  gates  and  weir  was  greatly 
encouraged. 

203.  Granite  Reef  Regulator. — The  regulator  at  the  head  of 
the  new  Arizona  canal  of  the  Reclamation  Service,  at  Granite 
Reef,  is  an  excellent  example  of  good  location  and  design.  The 
weir  (Art.  194)  is  set  at  right  angles  to  the  river  channel  and 
between  it  and  the  regulator  head  are  a  set  of  sluiceways  (Art.  196) 
set  in  an  extension  of  the  weir,  and  separated  from  the  latter  by 
a  training  wall,  at  right  angles  to  the  weir  axis,  which  directs  the 
stream  into  the  intake  basin  at  the  canal  head  and  in  front  of  the 


230  SLUICEWAYS,    REGULATORS,    AND    ESCAPES 

regulator.     The  sluiceways  and  regulator  are  in  a  straight  line 
with  the  weir,  a  continuation  of  its  axis  (Fig.  50). 

Separating  the  line  of  the  sluiceway  and  the  intake  basin  is 
a  concrete  weir  220  feet  in  length,  parallel  to  the  training  wall, 
77  J  feet  from  it,  and  with  its  crest  at  the  same  elevation,  1308 
feet,  or  2  feet  lower  than  the  crest  of  the  main  weir.  The  water 
falls  over  this  8  feet  to  the  floor  of  the  intake  basin,  the  elevation 
of  which  is  1300  feet.  The  river  bed  above  the  weir  and  without 
the  training  wall  has  an  elevation  of  1295  feet-  Tne  outer 
margin  or  bank  of  the  intake  basin,  forming  the  abutment  of  the 
regulator  gates,  is  a  paved  embankment  curved  on  a  radius  of 
116  feet,  which  is  the  width  of  the  regulator,  and  having  a  crest 
elevation  of  1325  feet,  or  15  feet  above  that  of  the  weir  crest  and 
sufficiently  high  to  assure  safety  from  topping  by  the  greatest  flood. 

204.  Classification   of   Regulators. — The   type   of    regulator 
employed  depends  upon  the  character  of  the  foundation  and  the 
permanency  deemed   desirable.     Regulators   may   be  classified 
according  to  the  design  of  the  gate  or  the  method  by  which  it  is 
operated.     With  nearly  any  type  of  foundation  varying  degrees 
of  permanency  may  be  given  the  superstructure  and  various 
methods  may  be  employed  for  operating  the  gates.     Accordingly 
regulators  are  classified  here  as  follows:   First,  wooden  gates  in 
timber  framing;    second,   wooden  gates   in   masonry   and   iron 
framing;   third,  iron  gates  in  masonry  and  iron  framing.     They 
are  further  classified,  according  to  the  method  of  operating  the 
gates,  as  follows:  First,  flashboard  gates;  second,  gates  raised  by 
hand  lever;   third,  gates  raised  by  chain  and  windlass;   fourth, 
gates  raised  by  screw  gearing. 

Simple  flashboard  or  needle  gates  should  be  used  only  where 
the  pressure  upon  them  is  low.  When  under  great  pressure  the 
opening  should  be  closed  by  a  simple  sliding-gate  raised  by  hand 
lever  or  windlass,  or  double  gates,  one  above  the  other,  may  be 
employed,  each  separately  raised  by  a  screw  and  hand  gear  from 
above. 

205.  General    Form    of    Regulator. — The    regulator    should 
be  so  constructed  that  the  amount  of  water  admitted  to  the  canal 
can  be  easily  controlled  at  any  stage  of  the  stream.     This  can 


ARRANGEMENT  OF  CANAL  HEAD         231 

be  done  only  by  having  gates  of  such  dimensions  that  they  can 
be  quickly  opened  or  closed  as  desired.  Accordingly,  when  the 
canal  is  large  and  its  width  great  the  regulator  should  be  divided 
into  several  openings,  each  closed  by  a  separate  and  independ- 
ent gate.  The  width  of  these  openings  should  be  rarely  less 
than  2  feet  nor  more  than  8  feet.  The  channel  of  the  regulator 
way  should  consist  of  a  flooring  of  timber  or  masonry  to  protect 
the  bottom  against  the  erosive  action  of  the  water,  and  of  side  walls 
or  wings  of  similar  material  to  protect  the  banks.  The  various 
openings  will  be  separated  by  piers  of  wood,  iron,  or  masonry, 
and  the  amount  of  obstruction  which  they  offer  to  the  channel 
should  be  a  minimum,  in  order  that  the  width  of  the  regulator 
head  shall  be  as  small  as  possible  for  the  desired  amount  of  open- 
ing. For  convenience  in  operation  it  is  customary  to  surmount 
the  regulator  by  arches  of  masonry  or  a  flooring  of  wood,  iron,  or 
reinforced  concrete,  so  as  to  give  an  overhead  bridge  from  which 
the  gates  may  be  handled.  Lastly,  the  height  of  the  regulating 
gates  and  the  height  of  the  bridge  surmounting  them  must  exceed 
the  height  of  the  weir  crest  by  the  amount  of  the  greatest  afflux 
height  which  the  floods  may  attain,  in  order  that  these  shall  not 
top  the  regulator  and  destroy  the  canal.  The  regulator  must  be 
firmly  and  substantially  constructed  to  withstand  the  pressure  of 
great  floods,  and  a  drift  fender  or  boom  should  be  built  immedi- 
ately in  front  of  or  at  a  little  distance  in  advance  of  the  gates. 
Wooden  regulator  heads  are  usually  constructed  much  as  are 
open  flumes,  arid  consist  of  a  fluming  or  boxing  of  timber  lined 
with  planks  on  the  bottom  and  sides  and  with  cross  bracing  above. 
In  this  are  set  the  piers  and  gates. 

206.  Arrangement  of  Canal  Head. — As  already  shown,  the 
regulator  gates  should  be  as  close  as  possible  to  the  end  of  the 
weir  in  order  to  prevent  the  deposit  of  silt  at  this  point.  Owing 
to  the  character  of  the  banks  and  to  avoid  excessive  cost  in  con- 
struction, it  is  sometimes  necessary  to  set  the  regulatorjback  in  the 
canal  a  short  distance.  In  such  cases  an  escape  should  be  in- 
troduced in  front  of  and  adjacent  to  it  to  relieve  it  of  pressure  and 
aid  in  its  effective  operation. 

At  the  head  of  the  Cavour  canal,  Italy,  the  regulator  is  set 


232  SLUICEWAYS,    REGULATORS,    AND    ESCAPES 

back  in  the  head  cut,  and  immediately  in  front  of  it  is  placed  an 
escape  discharging  into  the  river.  At  the  head  of  the  Turlock 
canal  in  California  the  flood  heights  are  so  great  that  the  water 
may  rise  above  the  weir  crest  to  a  height  of  16  feet.  In  order  to 
relieve  the  gates  of  this  pressure  the  canal  heads  directly  in  a  tun- 
nel which  is  560  feet  in  length  and  12  feet  wide  at  the  bottom  and 
is  cut  through  the  solid  rock.  It  discharges  into  an  open  rock 
cut  across  which  is  placed  the  regulator,  while  immediately  above 
and  at  right  angles  to  it  are  a  series  of  escape  gates  discharging 
back  into  the  river.  The  wasting  capacity  of  this  escape  is  made 
greater  than  the  possible  discharge  of  the  tunnel  under  the  great- 
est head  of  water,  so  that  the  regulator  gates  are  relieved  of  most 
of  the  pressure.  There  is  a  similar  arrangement  at  the  headworks 
of  the  Uncompahgre  canals  in  Colorado.  The  main  canal  is  sup- 
plied with  water  from  the  Gunnison  River  through  a  tunnel  30,- 
583  feet  in  length,  10  by  10  feet  in  section  and  having  a 
capacity  of  1300  second-feet  and  a  slope  of  2  feet  in  1000.  At 
the  lower  portal  the  canal  head  is  controlled  by  a  regulator  and 
escape. 

207.  Wooden  Flashboard  Regulators. — Simple  flashboard 
regulators  are  constructed  as  are  flashboard  weirs.  A  satisfac- 
tory regulator  of  this  kind  is  that  at  the  head  of  the  Calloway 
canal  in  California,  which  is  almost  identical  in  Construction  with 
the  weir  (Fig.  29)  and  therefore  scarcely  requires  description.  It 
consists  of  a  wooden  fluming  having  a  rectangular  cross-section 
built  into  the  canal  head  and  resting  on  piles  and  protected  by 
sheet  piling.  Above  and  below  this  regulator  head  are  built  a 
wooden  flooring  and  wings  to  prevent  erosion.  Flashboards  are 
laid  in  the  regulator  head  and  can  be  removed  or  replaced  one  at 
a  time,  according  to  the  amount  of  water  to  be  admitted. 

The  canal  regulator  on  the  Arizona  side  of  the  Laguna  weir 
(Art.  194)  is  nearly  parallel  to  the  course  of  the  Colorado  River 
at  this  point  (Fig.  55)  and  at  right  angles  to  the  line  of  sluiceways. 
It  is  219  feet  in  length  and  consists  of  34  openings,  each  7  feet 
6  inches  wide  by  10  feet  7  inches  high,  in  the  clear,  separated  by 
reinforced  concrete  piers  one  foot  in  thickness  and  topped  by  a 
bridge  of  the  same  material.  The  width  of  the  concrete  flooring 


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234 


SLUICEWAYS,    REGULATORS,    AND    ESCAPES 


under  the  regulator  is  17  feet  and  its  thickness  6  inches.  The 
gates  consist  of  18  planks  or  flashboards  of  Oregon  pine  4  inches 
x  6  inches  x  8  feet  to  each  opening.  These  are  removed  or 
replaced  one  at  a  time  by  hooked  poles  and  carried  on  a  car 

travelling  the  length  of  the  over- 
head bridge  (Fig.  67).  The 
effect  is  to  let  the  clearer  water 
into  the  canal  by  skimming  it 
from  the  top  of  the  river. 

208.  Wooden  Gate  lifted  by 
Windlass. — One  of  the  most 
notable  examples  of  this  type  of 
gate  is  that  at  the  head  of  the 
Ganges  canal  in  India,  the  regu- 
lator of  which  is  of  masonry,  the 
gates  being  separated  by  masonry  piers.  The  head  on  the  gates 
is  such  that  it  is  necessary  to  have  three  tiers  of  gates  one  above 
the  other,  the  most  advanced  or  up-stream  gate  having  its  sill  on 


FIG.  68. — Regulator  Gates,  Ganges 
Canal. 


Lover  an 

Cafe  full  cjecn. 


Both 


yatt  optn 
FIG.  69.  —  Regulator  Gates,  Soane  Canal,  India. 


a  level  with  the  canal-bed  and  the  two  higher  gates  having  their 
sills  each  6  feet  higher,  while  they  retrograde  toward  the  face  of 
the  bridge  by  the  width  of  a  gate.  On  the  bridge  above  are  two 


GATE    LIFTED    BY   TRAVELLING   WINCH 


235 


simple  horizontal  wooden  windlasses,  and  the  gates  are  raised  by 
turning  these. 

209.  Gate  Lifted  by  Travelling  Winch. — This  is  the  most 
common  form  of  gate  employed  in  India,  where  the  width  of  canal 
head  is  great  and  the  number  of  openings  correspondingly  large, 
as  also  at  the  Laguna  weir,  Colorado  River.  (Art.  195.)  As 
shown  in  Fig.  69,  for  the  Soane  canal  regulator,  the  gate  is  con- 
structed of  wood,  cross-braced,  and  to  its  top  are  attached  chains 
which  run  over  the  windlass  of  the  travelling  winch.  Above  these 


FIG.  70. — Wooden  Lever  and  Screw  Regulator  Gates. 

gates  is  a  bridge,  and  on  the  parapet  immediately  over  the  gates 
is  a  simple  railroad  track  on  which  a  handcar  is  run.  On  this  is 
placed  a  simple  hand  winch,  and  by  turning  this  each  gate  can  be 
successively  raised  or  lowered  and  the  winch  pushed  along  to  the 
next  gate. 

210.  Gate  Raised  by  Gearing  or  Screw. — This  is  the  most 
usual  type  of  gate  in  this  country  and  abroad.  They  are  em- 
ployed where  there  is  some  pressure  to  be  overcome  and  as  they 
are  slow  in  operation,  gates  raised  by  levers  are  generally  inserted 
in  a  few  of  the  openings  (Fig.  70),  to  be  used  when  the  pressure 


236 


SLUICEWAYS,    REGULATORS,    AND    ESCAPES 


is  light,  geared  gates  being  employed  in  the  remainder.  Above 
the  gate  projects  a  heavy  steel  screw,  and  this  passes  through  a 
female  screw  of  bronze  or  malleable  iron  on  which  the  wear  is  taken 
up.  As  the  pressure  which  this  gate  has  to  withstand  is  high,  the 
simple  screw  is  not  sufficient,  and  the  female  screw  forms  the  inner 
surface  or  axis  of  a  geared  or  cogged  wheel  which  is  turned  by  a 
smaller  cog  operated  by  a  hand  wheel;  thus  the  gate,  while 
moving  very  slowly,  can  be  raised  with  the  application  of  but  a 
trifling  amount  of  power,  owing  to  the  multiplicity  of  gearing 


.Standard  gate  stand 
/furnished  by  U.S.R.S. 


SECTIONAL  ELEVATION 
FIG.  71. — Regulator  Gate,  Leasburg  Canal,  Rio  Grande,  N.  Mex. 

employed.  This  type  of  gate,  as  adopted  for  the  Reclamation 
Service,  is  illustrated  in  the  wooden  gate  at  the  head  of  the  Leas- 
burg  canal,  New  Mexico — Texas  (Figs.  71  and  72).  The  corres- 
ponding iron  gate  is  illustrated  in  the  headworks  of  the  Minidoka 
canal,  Idaho  (Fig.  73).  In  this  the  screw  is  threaded  at  the  lower 
end  and  works  in  nuts  fastened  to  the  gate,  thus  lifting  it. 

211.  Inclined,  Horizontally  Pivoted  Falling  Gates. — The 
regulator  heads  to  some  of  the  branch  canals  on  the  Goulburn 
Irrigation  System,  Australia,  consist  of  a  series  of  fourteen  gates 
each  7  feet  high  by  10  feet  wide,  placed  across  the  channel  and 


INCLINED,    HORIZONTALLY    PIVOTED    FALLING    GATES      237 

arranged  to  maintain  the  surface  of  the  water  at  the  offtakes  at 
any  desired  height.  The  gates  are  of  wrought  iron,  fitted  with 
rollers  at  the  head,  worked  in  vertical  recesses  in  cast-iron  piers 
and  on  roller  bearings  carried  on  horizontal  shafts,  supported 
on  pedestals  secured  to  the  stonework  in  the  masonry  bed  of  the 
regulator  head  and  to  the  piers  (Fig.  74).  These  roller  bearings 
are  a  little  below  the  lower  third  of  the  gates.  The  motion  of  the 
gates  is  peculiar,  being  vertical  at  the  head,  forward  in  raising  and 


CROSS  SECTION 

DETAILS  OF  GATE 


FIG.  ^^. 


FIG.  72. 

FIG.  72.— Wooden  Gate/Leasburg  Canal  Regulator,  Rio  Grande,  N.  Mex. 
FIG.  73.— Iron  Regulator  Gate,  Minidoka  Canal,  Idaho. 

backward  in  lowering  on  the  roller  bearings  so  that  the  pressure 
on  them  may  be  nearly  balanced  in  all  positions  and  so  that  a  mini- 
mum power  may  be  required  to  work  them.  Each  gate  is  manip- 
ulated by  separate  gearing,  consisting  of  a  screw  shaft  with  eye- 
and-pin  connection  to  the  gate-head,  worked  by  a  bevel-wheel 
gearing  into  a  pinion  operated  by  windlass  from  the  bridge  above. 
One  of  the  most  desirable  results  of  this  form  of  regulator  head  is 


238  SLUICEWAYS,    REGULATORS,    AND   ESCAPES 


Scale 


I  I  I  I          I          I/ 


PLATE  XII. — Elevation  and  Cross-section  of  Weir  and  Regulator,  Bear  River 

Canal,  Idaho. 


HYDRAULIC    LIFTING    GATES  239 

in  the  fact  that  the  water  is  drawn  off  the  surface  of  the  canal,  and 
thus  is  freer  of  silt  than  if  it  were  taken  from  the  bottom. 

212.  Hydraulic  Lifting  Gates. — At  the  head  of  the  Folsom 
canal  in  California  the  regulating  gates    are  operated    by    hy- 
draulic    power    from     an    accumulator    fed     by     water-power 
from  a  fall  in  the  canal.     This  regulator  is  constructed  in  the 
most  substantial  manner  of  granite  masonry,  and   has  a  total 
width  of  66  feet  between  abutments.     The  gates  CP1.  XIII)  are 
three  in  number,  each  16  feet  in  width  and  14  feet  in  height  to 
the  crest  of  a  semicircular  arch,  and  are  separated  by  masonry 
piers  6  feet  in  thickness.     They  are  of  wood,  well  braced,  and 
slide  vertically  in  grooves  let  into  the  masonry  piers  separating 
them.     One  hydraulic  jack  is  attached  to  each  gate,  and  its  cylin- 
der is  fastened  to  the  masonry  above.    In  this  works  a  steel  plunger 
having  a  1 4-foot  stroke  and  directly  connected  at  its  lower  end 
with  the  gate. 

213.  Wasteways. — In  order  to  establish  complete  control  over 
the  water  in  a  canal  channel  provisions  should  be  made  for  dis- 
posing of  any  excess  which  may  arise  from  sudden  rains  or  floods 
or  from  water  not  required  for  irrigation.     This  is  effected  by 
means  of  escapes,  or,  as  they  are  more  commonly  called  in  this 
country,  wasteways  or  spillways.     These  are  short  cuts  from  the 
canal  to  some  natural  drainageway  into  which  the  excess  of  water 
can  be  discharged.     Wasteways  perform  the  additional  service 
of  flushing  the  canal  and  thus  preventing  or  scouring  out  silt 
deposits. 

If  the  heads  of  distributaries  be  opened  the>i relieve  the  main 
canal,  and  the  former  are  in  turn  relieved  by  opening  the  waste- 
ways;  hence  the  distributary  heads  act  as  the  safety-valves  and 
the  wasteways  as  the  waste-pipes  of  a  canal  system.  Wasteways 
should  be  provided  at  intervals  along  the  entire  canal  line,  the 
lengths  of  the  intervals  depending  on  the  topography  of  the  sur- 
rounding country,  the  danger  from  floods  or  inlet  drainage,  and 
the  dimensions  of  the  canal.  On  large  canal  systems  in  India  it 
is  customary  to  place  them  at  intervals  from  20  to  40  miles.  In 
our  own  country  they  are  placed  more  frequently,  usually  10  to 
20  miles  apart.  Where  the  regulator  head  is  placed  back  from 


240  SLUICEWAYS,    REGULATORS,    AND    ESCAPES 

the  river  a  short  distance,  as  in  the  case  of  the  Cavour,  Uncom- 
pahgre,  and  Turlock  canals,  a  wasteway  should  be  provided 
immediately  above  the  regulator  head  for  the  discharge  of  surplus 
water  and  to  keep  the  channel  free  from  silt.  The  first  or  main 
wasteway  on  a  canal  line  should  be  at  a  distance  not  greater  than 
half  a  mile  from  the  regulator,  in  order  that  in  case  of  accident 
to  the  canal  the  water  may  immediately  be  drawn  off.  This 
main  wasteway  has  the  additional  advantage  of  acting  as  a 
flushing  gate  for  the  prevention  and  removal  of  silt  deposits. 
Where  used  for  the  latter  purpose  it  is  customary  to  decrease  the 
slope  of  the  canal  between  its  head  and  the  escape,  in  order  that 
matter  carried  in  suspension  may  be  deposited  at  that  point. 

214.  Location  and  Characteristics  of  Wasteways. — Waste- 
ways  should  be  located  above  weak  points,  as  embankments, 
flumes,  etc.,  that  the  canal  may  be  quickly  emptied  in  case  of 
accident.  Their  position  should  be  so  chosen  that  the  waste 
channels  through  which  they  discharge  shall  be  of  the  shortest 
possible  length.  These  must  have  sufficient  discharge  to  carry 
off  the  whole  body  of  water  which  may  reach  them  from  both 
directions,  so  that  if  necessary  the  canal  below  the  escape  may 
be  laid  bare  for  repairs  while  it  is  still  in  operation  above. 

The  greatest  source  of  danger  to  canals  is  during  local  rains, 
when  the  irrigator  ceases  to  use  the  water,  thus  leaving  the  canal 
supply  full,  while  its  discharge  is  augmented  by  the  flood  waters. 
Hence  it  is  essential  that,  where  a  drainage  inlet  enters  the  canal, 
a  wasteway  be  placed  opposite  for  the  discharge  of  surplus  water. 
During  floods  the  wasteway  acts  in  relieving  the  canal  as  though 
the  head  regulator  had  been  brought  that  much  nearer  the  point 
of  application.  That  the  wasteway  may  act  most  effectively  the 
slope  of  its  bed  should  be  increased  by  at  least  12  inches  immedi- 
ately below  its  head,  in  addition  to  which  the  slope  of  the  re- 
mainder of  the  bed  should  be  a  little  greater  than  that  of  the  canal, 
and  it  should  tail  into  the  drainage  channel  with  a  drop  of  a  few 
feet.  Wasteways  are  sometimes  built  in  the  sides  of  flumes, 
thereby  avoiding  the  expense  of  constructing  a  waste  channel, 
as  the  water  is  discharged  immediately  into  the  drainage  channel 
beneath  the  flume.  While  this  practice  is  economical  and  may 


LOCATION   AND    CHARACTERISTICS    OF    WASTEWAYS       241 


P* 

bC 


242  SLUICEWAYS,    REGULATORS,    AND    ESCAPES 

serve  well  where  cheap  construction  is  necessary,  it  is  far  from 
the  best  method  unless  great  care  is  taken.  The  water  falling 
from  the  flume  may  damage  its  foundations  while  the  wasteway 
does  not  add  to  the  security  of  the  structure  in  which  it  is  placed, 
and  does  not  shut  off  the  water  above  it. 

215.  Design  of  Escape  Heads. — Spillways  and  the  regulators 
placed  in  the  canal  adjacent  to  and  below  them  are  built  on 
similar  designs  to  the  main  regulating  gates  at  the  head  of  the 
canal.  A  maximum  limit  is  given  to  the  dimensions  of  each  gate, 
and  as  many  are  inserted  as  are  necessary  to  pass  the  entire  dis- 
charge of  the  canal  without  obstructing  its  velocity.  These  gates 
may  be  of  wood  or  iron,  and  may  be  framed  between  timber, 
iron,  or  masonry  piers  and  abutments.  They  are  operated  as 
are  the  head  regulating  gates;  but  as  the  pressure  on  them  is 
never  great  some  simple  form  of  lifting  apparatus,  as  flashboards 
or  sliding  gates  raised  by  hand  lever,  windlass,  or  simple  screw, 
is  sufficiently  effective. 

On  the  Galloway  canal  in  California  wood  en  flashboard  escape- 
gates  are  used  which  are  similar  to  the  Galloway  falls  and  regu- 
lating gates  (Fig.  29).  On  the  Highline  canal  in  Colorado  the 
first  main  wasteway  is  in  the  bench  flume  600  feet  below  the  head 
regulator,  and  consists  of  a  set  of  four  wooden  gates,  each  3  by  4 
feet,  set  into  the  side  of  the  flume  and  raised  by  simple  rack  and 
pinion  (PL  XIX).  In  the  flume  below  and  adjacent  to  this  are 
a  set  of  flashboard  checks  for  regulating  the  discharge  of  the 
canal,  or  of  closing  it  and  forcing  all  the  water  through  the  waste- 
way.  On  the  Bear  River  canal,  Utah,  there  are  two  head  waste- 
ways,  one  1 200  feet  and  the  other  1800  feet  below  the  head  regula- 
ting gates,  and  discharging  back  over  the  canyon  sides  into  the 
river.  Each  of  these  has  12  feet  of  clear  opening  closed  by  three 
wooden  gates  sliding  between  iron  posts  and  raised  by  screw 
gearing.  Below  and  adjacent  to  the  lower  wasteway  is  a  set  of 
regulating  gates  in  the  canal. 

On  the  line  of  the  Turlock  canal  abundant  wasteway  has  been 
provided,  as  the  canal  flows  in  natural  drainage  channels  for  a 
portion  of  its  course.  One  of  these,  Dry  Creek,  has  a  large  catch- 
ment basin,  and  the  diverting  dam  which  turns  the  water  back 


DESIGN    OF   ESCAPE   HEADS 


243 


244 


SLUICEWAYS,    REGULATORS,    AND    ESCAPES 


into  the  canal  is  provided  with  a  spillway  51  feet  in  length,  be- 
sides a  wasteway,  30  feet  in  length.  An  interesting  wasteway  on 
this  canal  is  in  the  bottom  of  the  flume  crossing  Peasley  Creek. 
This  flume  is  20  feet  wide  and  7  feet  deep,  and  is  carried  on  a 
trestle  60  feet  in  height  above  the  stream  bed.  In  the  flume 
bottom  is  built  an  escape  which  is  of  capacity  sufficient  to  dis- 
charge the  full  volume  of  water  in  the  flume.  It  is  built  by  laying 
an  iron  beam  across  the  flume  bed,  and  this  revolves  on  an  axis 
turned  by  means  of  a  hand  wheel,  thus  converting  a  portion  of  the 
floor  into  a  revolving  gate  by  opening  the  bottom  of  the  flume 
for  its  entire  width.  Beneath  this  gate  is  a  receiving  box  which 


TRANSVERSE  SECTION 
LONGITUDINAL  SECTION 

FIG.  75. — Escape-flume  on  Goulburn  Canal,  Australia. 

discharges  up  and  down  stream  into  two  inclined  wooden  flumes 
which  lead  the  water  into  the  creek. 

Escapes  are  provided  on  the  Goulburn  canal  in  Australia  by 
building  them  in  the  floors  of  the  flumes  which  cross  occasional 
drainage  lines.  The  first  is  in  the  seventh  mile  and  consists  of 
three  openings  in  the  floor  of  the  flume,  fitted  with  valves  opening 
downward  and  worked  from  a  gangway  above  by  screw  and  lever 
gearing  (Fig.  75).  These  escapes  serve  the  purpose  of  regulating 
the  supply  by  disposing  of  surplus  water,  and  also  act  as  sand 
gates. 

216.  Wasteways,  Reclamation  Service. — Reinforced  concrete 
is  used  extensively  by  the  Reclamation  Service  to  protect  canal 
banks  or  earth  slopes  at  wasteway  openings,  as  on  all  other 
structures  on  these  government  works.  A  type  of  the  smaller 


WASTEWAYS,   RECLAMATION    SERVICE 


245 


wasteway  in  canal  banks  is  that  in  the  Fort  Shaw  canal,  Montana 
(Fig.  76).  On  the  canal  side  is  a  vertical  wall  of  concrete  3  feet 
high  and  8  inches  thick,  reaching  below  the  level  of  the  canal  bed. 


PLAN 


SCALE   OF  FCF.1 
1    0  1  *   »   4   &  10 


H»*£L  8ML9 

•X^*    "V.    **  n»S    _j^8 


SECTION 
FlG.  76. — Spillway,  Fort  Shaw  Canal,  Montana. 

This  supports  the  lower  edge  of  the  4"  reinforced  concrete  floor  of 
the  spillway  opening  which  reaches  to  maximum  water  level  and 
slopes  thence  beyond  the  outer  bank.  On  the  Lower  Yellowstone 
canal,  North  Dakota  (Fig.  77),  this  form  of  spillway  is  slightly 


Present  Surface 
of  Ground 

Structure  to  be  reinforced 
throughout  with  )$"sq.  steel 
bars  spaced  12  Vs  both  way. 
equidirt.  from  concrete  faces 


FIG.  77. — Standard  Sluiceway,  Lower  Yellowstone  Canal,  Montana-North  Dakota. 

modified  and  the  concrete  flooring  is  6  inches  in  thickness.  The 
reinforcement  in  both  cases  is  of  \  inch  square  steel  spaced 
12  inches  centers  both  ways.  The  latter  wasteway  discharges  into 


246 


SLUICEWAYS,   REGULATORS,    AND   ESCAPES 


a  third  channel  paralleling  the  canal  for  a  short  distance  and 
turning  .thence  down  slope  to  a  drainage  channel. 

A  by-pass  between  the  storage  feed  canal  and  one  of  the  main 
canals  on  the  Umatilla  project,  Oregon,  is  not  dissimilar  in  design 
to  a  wasteway  excepting  that  its  entrance  is  closed  by  regulator 
gates  for  control  of  the  volume  of  water  passed  to  the  distributary 
canal.  The  total  fall  between  canals  is  15  feet,  the  slope  of  the 
6-inch  reinforced  concrete  floor  being  3  to  i  near  the  top  and  4 


Fig.  78. — Pine  Ridge  Sluiceway,  Interstate  Canal,  Nebraska-Wyoming. 

to  i  below,  and  its  length  85  feet  (Fig.  79).  The  lower  end  of 
the  wasteway  is  closed  by  a  concrete  weir  8  ft.  high,  the  crest  of 
which  is  about  i  ft.  above  the  water  surface  in  the  lower  canal. 
The  sloping  floor  is  supported  at  intervals  of  about  15  feet  by 
concrete  cross  walls  3  feet  high  and  12  inches  thick. 

217.  Taintor  Circular  Wasteway  Gates. — On  the  Lower 
Truckee  canal  are  two  main  wasteways,  the  first  or  upper  of 
which  is  4.6  miles  from  the  head.  The  lined  canal  section  ad- 
joining the  wasteway  basin  has  20.8  feet  base  and  i  to  i  slopes. 


f 

TAINTOR    CIRCULAR   WASTEWAY  GATES 


247 


248  SLUICEWAYS,   REGULATORS,    AND    ESCAPES 

The  basin  is  formed  by  dropping  the  canal  bed  6  feet  vertically 
for  a  distance  of  45  feet  and  by  widening  it  on  the  lower  side, 
making  a  chamber  45  by  about  36  feet  on  the  bottom  and  19  feet 
deep  when  the  canal  is  full.  In  the  wall  forming  the  lower  side 
of  the  basin  are  five  wasteway  openings,  each  5  by  5  feet  in  the 
clear  with  a  head  of  14  feet  over  the  top.  The  openings  are 
separated  by  piers  4  feet  wide  and  lofeet  long,  the  spaces  between 
the  piers,  above  the  top  of  the  openings,  being  closed  up  by  2  feet 
of  reinforced  concrete  set  back  2  feet  from  the  upper  edge  of  the 
piers. 

The  passage  of  water  through  each  of  the  five  openings  is 
regulated  by  a  gate  of  the  Taintor  pattern,  which  consists  of  a 
circular  arc  revolving  around  a  horizontal  shaft,  to  which  it  is 
attached  by  radial  arms,  the  whole  forming  in  outline  a  sector 
of  a  circle.  The  arc  is  convex  toward  the  water  pressure,  which 
is  transmitted  as  thrust  by  the  radial  arms  directly  to  the  shaft. 
The  center  of  the  shaft  is  at  the  same  level  as  the  top  of  the  gate 
opening.  The  radius  to  the  outside  or  bearing  surface  of  gate 
is  7  feet  5!  inches.  The  arc  has  a  net  length  of  5  feet  5§ 
inches,  and  subtends  an  angle  of  41°  53'.  The  required  net 
horizontal  length  of  the  gate  surface  is  5  feet.  The  steel  shaft  is 
4  inches  in  diameter  and  7  feet,  if  inches  in  length.  From  the 
shaft  radiate  three  cross  frames,  constructed  of  3  by  3  by  J  inch 
angle  irons.  At  the  outer  ends  these  support  the  circular  part 
of  the  gate  which  is  built  up  of  angles,  plates,  and  5-inch  I-beams. 
The  sheathing  by  which  the  water  is  excluded  is  of  one-fourth 
inch  steel  plate.  When  entirely  closed  the  lower  end  of  the  gate 
has  a  contact  of  about  4  inches  with  a  guide  strip  set  in  the  floor, 
and  the  upper  end  has  a  light  contact  with  a  strip  next  to  the  top 
of  the  opening.  The  side  edges  of  the  gate  also  have  contact 
with  corresponding  strips  on  the  sides  of  the  concrete  piers.  The 
lower  portion  of  the  piers  for  over  5  inches  on  each  side  is  recessed, 
to  make  room  for  the  full  width  of  the  gates,  which  is  about  5! 
feet.  The  contact  or  bearing  surfaces  of  the  gate  and  the  guides 
are  made  of  bronze  5/6-inch  thick. 

The  gate  is  raised  by  a  i^-inch  steel- wire  cable,  attached  to 
its  upper  edge.  The  cable  extends  upward  to  and  around  a 


TAINTOR    CIRCULAR   WASTEWAY   GATES 


249 


250 


SLUICEWAYS,    REGULATORS,    AND    ESCAPES 


grooved  drum  on  top  of  the  wall  between  piers.  The  drums  for 
all  the  gates  are  keyed  with  a  2j-inch  steel  shaft.  Power  is 
applied  to  the  shaft  through  a  pinion  and  geared  wheel  at  either 
end  of  this  shaft,  which  is  43^  feet  long.  The  pinion  is  turned 
by  a  crank  by  hand.  The  crank  radius  is  18  inches,  the  pinion 
is  about  6  inches  and  the  geared  wheel  32  inches  in  diameter, 
while  the  drum  is  8  inches,  making  the  multiplication  of  power  24. 
The  power  available  for  lifting  a  gate,  even  if  each  of  the  two 


FIG.  8 1. —Cross-section  of  Sand-box,  Santa  Ana  Canal. 


gears  be  worked,  is  too  small  to  readily  lift  the  gate  without  some 
other  aid.  The  entire  length  of  shaft  has  to  be  turned,  and  con- 
siderable power  is  required  for  this  alone,  besides  overcoming 
other  frictions.  The  gates  are  counterweighted  as  follows:  A 
TV-inch  cable  leads  from  the  same  point  of  attachment  up  to  two 
1 8-inch  sheaves,  on  a  level  with  top  of  the  piers  and  3  feet  apart. 
From  the  rear  sheave  depends  a  bucket  of  15  cu.  ft.  capacity, 
which  may  be  filled  with  water  to  nearly  counterweigh  the  gate. 

218.  Sand-gates. — Sand-gates     are    practically    waste-gates, 
though  they  are  so  designed  and  arranged  in  some  canals  as  to 


SAND-GATES 


be  of  service  only  in  scouring  or 
removing  silt  deposits.  The 
main  or  head  wasteway  on  a 
canal  system  acts  as  a  sand-gate, 
and  is  generally  built  as  much 
for  the  purpose  of  flushing  and 
scouring  sediment  as  for  the 
control  of  water  in  the  canal. 
The  gate  in  the  Highline  flume 
acts  effectively  as  a  sand-gate, 
because  a  board  check  from  i  to 
2  feet  in  height  is  placed  across 
the  flume  below  the  escape  head. 
This  causes  the  deposit  of  silt 
immediately  above  it,  whence  it 
can  be  removed  by  the  scour 
through  the  escape. 

Careful  provision  has  been 
made  for  the  removal  of  silt  on 
the  Folsom  canal.  Immediately 
in  front  of  and  above  the  regu- 
lating head  is  a  set  of  four  sand- 
gates  placed  6  feet  below  the 
grade  of  the  canal  and  discharg- 
ing directly  back  into  the  river. 
These  are  practically  undersluice 
gates,  and  are  each  5  by  6  feet 
in  the  clear  and  set  in  substan- 
tial masonry.  Sediment  which 
is  dropped  into  the  subgrade  in 
the  canal  opposite  these  gates  is 
scoured  out  through  them.  In 
addition  to  these  sand-gates, 
seven  others  are  placed  in  the 
first  1700  feet  of  the  canal. 
These  are  all  similar  in  construc- 
tion, 5  feet  wide  by  10  feet  high, 


252 


SLUICEWAYS,    REGULATORS,    AND    ESCAPES 


framed  in  substantial  masonry,  and  consist  of  iron  gates  sliding 
vertically  and  raised  by  means  of  a  hand  wheel  and  endless  screw 
working  on  ratchets  set  on  the  back  of  the  gate.  Across  the  bed 
of  the  canal  opposite  and  below  each  of  these  sand-gates  is  a 
subchannel  and  catch-basin  i  foot  in  depth,  the  object  of  which 
is  to  collect  silt  which  is  afterwards  scoured  out  through  the  gates. 
An  excellent  though  expensive  form  of  sand-gate  is  that  on 


I    -1^"  Single 
Thread 


TOP  VIEW 


VA  Steel 


•g 

"w     ft 


s 


6 'x  6  "Wooden 
Sill 


•e 


-ll-r-U. n -u- 


•*      d 

FRONT  VIEW 


SEC.    C-d 


SEC.  a-b 
FIG.  83. — Cast-iron  Sluice-gate,  Interstate  Canal,  Nebraska-Wyoming. 

the  Santa  Ana  canal.  The  main  feature  of  this  is  the  sand-box 
or  enlargement  of  the  canal  in  which  the  sediment  is  caused  to 
be  deposited.  These  sand-boxes  are  placed  on  the  line  of  a 
flume,  and  into  them  the  water  is  discharged,  and  because  of 
their  increased  cross-section  the  velocity  of  the  water  is  checked 
and  the  sediment  deposited.  The  first  sand-box  is  60  feet  long 


SAND-GATES 


253 


by  13  feet  wide,  and  its  floor  slopes  transversely  (Fig.  81)  and  is 
broken  into  longitudinal  profiles  by  three  partitions,  the  level 
tops  of  which  are  6  feet  6  inches  below  the  surface  level  and  are 
15  feet  apart  from  center  to  center.  They  are  so  arranged  as  to 
divide  the  bottom  of  the  chamber  into  four  compartments.  To 
each  of  these  sumps  the  bottom  of  the  chamber  slopes,  and  in 
each  is  located  a  hollow  cast-iron  cone  sand-valve,  which  opens 
down  into  a  culvert  leading  to  an  escapeway. 

Sluiceways  of  standard  pattern  are  provided  on  the  lower 
Yellowstone  canal  which  are  so  designed  as  to  perform  also  the 
offices  of  sand-gates.  In  the  line  of  the  canal,  at  convenient 


K— -8'o?—  -U 


Canal 
Water  Surface 


FIG.  84. — Sand  Box,  Leasburg  Canal,  Rio  Grande,  New  Mexico. 

crossings  of  depressions,  are  basins  of  reinforced  concrete  de- 
pressed 5  feet  below  the  level  of  the  canal  bed,  the  width  of  the 
basin  parallel  to  the  line  of  canal  being  26  ft.  at  top  and  12  ft.  at 
bottom.  In  these  sediment  will  settle  and  they  may  be  dis- 
charged, flushing  the  sediment  or  wasting  the  canal  water  as 
desired,  through  two  openings  5'  wide  and  12  ft.  high,  controlled 
by  iron  gates  operated  from  an  overhead  bridge  by  standard 
Reclamation  Service  screw  and  cogged  gearing  (Figs.  82 
and  83). 

On  the  Leasburg  canal  of  the  Reclamation  Service  in  New 
Mexico  is  quite  an  elaborate  sand-gate  of  reinforced  concrete, 
necessitated  by  the  heavy  deposits  of  silt  left  by  the  waters  of  the 
Rio  Grande.  There  is  a  sand-box  or  depression  in  the  line  of 
the  canal,  of  3  feet  depth.  This  discharges  through  a  culvert 


254  SLUICEWAYS,   REGULATORS,    AND   ESCAPES 

19  feet  wide  by  2  J  feet  high  under  the  canal  bank.  The  entrance 
to  this  culvert  is  in  a  concrete  retaining  wall  supporting  the  canal 
bank,  and  is  controlled  by  four  ribbed  iron  gates  3  feet  6  inches 
wide  by  2  feet  8  inches  high.  When  raised  the  canal  water 
flushes  out  the  sand  collected  in  the  canal  bed  or  sand-box.  The 
canal  bed  approaching  the  sand-box  is  2  feet  6  inches  lower  than 
beyond  the  box.  Hence  the  total  depth  of  the  sand-box  on  the 
down  stream  side  is  5  feet. 


CHAPTER  XII 

FALLS    AND    DRAINAGE    WORKS 

219.  Excessive  Slope. — As  the  fall  of  the  country  through 
which  a  canal  runs  is  usually  greater  than  the  slope  of  the  canal, 
the  tendency  of  the  water  in  the  latter  is  to  erode  its  bed.     When 
this  erosive  action  is  extended  to  long  reaches  of  the  channel  it 
produces  retrogression  of  levels.     If  the  canal  is  straight  little 
harm  is  done,  other  than  to  cause  the  level  of  the  water  to  sink 
below  the  ground  surface  and  impede  its  diversion.     Where  it  is 
necessary  to  divert  the  water,  or  where  there  are  curves  which  the 
increased  erosive  action  of  the  water  would  injure,  it  becomes 
necessary  to  compensate  for  the  difference  between  the  slope  of 
the  country  and  the  canal-bed,  so  as  to  reduce  the  velocity.     This 
is  done  by  concentrating  the  difference  of  slope  in  a  few  points 
where  vertical  falls  or  rapids  are  introduced.     The  location  of 
these  is  usually  fixed  by  the  place  where  the  canal  comes  too  high 
above  the  surface  of  the  ground,  while  their  distance  apart  is  so 
arranged  that  they  shall  not  have  an  excessive  height  or  fall.     If 
a  canal  can  be  so  located  and  aligned  that  it  will  skirt  the  slopes  of 
the  country  on  a  grade  contour,  it  becomes  possible  to  give  it  the 
most  desirable  slope  throughout  its  length  without  the  introduc- 
tion of  falls;    but  where  it  runs  down  the  slope  of  the  country, 
compensation  must  be  made  for  the  difference  between  the  ex- 
cessive ground  slope  over  that  of  the  canal. 

220.  Falls  and  Rapids. — There  are  two  general  methods  of 
compensating  for  slope;    one  is  by  the  introduction  of  vertical 
drops  or  falls,  and  the  other  by  the  use  of  inclined  rapids  or  chutes. 
Falls  and  rapids  are  of  various  kinds  and  may  be  generally  classi- 
fied according  as  they  are  of  wood  or  masonry.     In  design  the 
fall  may  be  of  three  general  types:  i,  it  may  have  a  clear  vertical 
drop  to  a  wooden  or  masonry  apron;   2,  the  lower  face  of  the  fall 
may  be  given  an  ogee-shaped  curve  (Article  176),  with  the  object 

255 


256  FALLS    AND    DRAINAGE   WORKS 

of  diminishing  the  velocity  and  consequent  erosive  action  of  the 
water;  3,  the  water  may  plunge  into  a  water-cushion  (Article  177). 
To  prevent  the  scour  above  the  fall  induced  by  the  increased 
velocity  of  approach:  i,  a  flashboard  weir  may  be  erected  at  the 
crest;  2,  the  channel  may  be  contracted,  or  3,  gratings  may  be 
introduced.  To  prevent  the  erosive  action  in  the  lower  level  at 
the  foot  of  the  fall  a  water-cushion  may  be  employed,  or  the  chan- 
nel may  be  increased  in  width,  terminating  in  wings  which  shall 
deflect  the  eddies  back  against  the  fall. 

221.  Retarding  Velocity  by  Flashboards  on  Fall  Crest— 
The  effect  of  a  fall  is  to  increase  the  velocity  and  to  diminish 
the  depth  of  water  for  some  distance  above  it.  This  increase  of 
velocity  produces  a  dangerous  scour  on  the  bed  and  banks  of  the 
canal,  which  in  a  properly  constructed  fall  is  guarded  against  by 
means  of  flashboards  or  by  narrowing  the  width  of  the  channel. 
The  height  to  which  it  is  necessary  to  raise  the  crest  of  the  fall  is 
found  by  the  following  formula  devised  by  Colonel  J.  H.  Dyas 
of  the  Indian  Engineers  : 

2^)'--MS.8iM?l,      ....       (4) 

in  which  h  ==  height  in  feet  of  the  water  surface  above  the  crest 

of  the  fall; 

a  =  the  sectional  area  of  the  open  channel  in  square  feet; 
r  =  the  hydraulic  mean  depth  of  the  same  in  feet  ; 
/  =  the  length  of  the  crest  of  the  fall  in  feet  ; 
/  =  the  length  of  slope  to  a  fall  of  one  in  the  same. 

This  formula  has  been  somewhat  modified  by  Mr.  P.  J.  Flynn 
in  order  to  make  it  agree  with  Kutter's  formula.  Mr.  Flynn 
finds  the  discharge  over  the  fall  complete  to  be 


in  which  Q  =  the  discharge  in  second-feet; 

c   =  the  coefficient  of  discharge  of  open  channel  ; 

m  =  coefficient  of  discharge  over  a  weir,  and  varies  be- 

tween 2.5  and  3.  5; 
s  =  the  sign  of  slope;  and  finally  he  gives  the  following: 


RETARDING    VELOCITY    BY    CONTRACTING    CHANNEL      257 


If  from  this  value  of  h  we  deduct  the  depth  of  water  in  the  chan- 
nel, we  have  the  height  to  which  the  weir  must  be  raised  above 
the  bed  of  the  canal  in  order  that  the  water  shall  not  increase  in 
velocity  in  approaching  the  crest  of  the  fall. 

222.  Retarding  Velocity  by  Contracting  Channel.  —  If,  instead 
of  raising  the  crest  of  the  fall,  it  is  desired  to  narrow  the  channel 
above  the  fall  in  order  to  diminish  the  velocity  of  approach  and 
the  consequent  erosive  action,  the  amount  of  narrowing  may  be 
calculated  by  the  common  weir  formula  (No.  2)  above  given,  and 
substituting  for  Q  its  value  ac  (rs)  J,  and  transposing  we  finally  get 


_  zagc 

:<~ 


in  which  /  is  the  length  of  the  weir  crest  or  the  width  of  the  chan- 
nel immediately  above  the  fall,  in  feet. 

223.  Gratings  to  Retard  Velocity  of  Approach.  —  Gratings,  for 
the  purpose  of  retarding  the  velocity  of  approach  to  the  crest  of 
falls,  are  used  with  excellent  results  on  some  canals  in  India,  and 
more  recently  by  the  Reclamation  Service.  They  consist  of  a 
number  of  inclined  bars  placed  just  above  the  crest  of  the  fall. 
The  method  of  spacing  these  is  such  that  the  velocity  of  no  one 
part  of  the  stream  shall  be  either  increased  or  retarded  by  the 
proximity  of  the  fall.  The  bars  may  be  of  wood  or  iron  and  rest 
on  one  or  more  overhead  cross-beams  and  are  laid  at  a  slope  of 
about  i  on  3,  and  are  made  of  such  length  that  the  full  supply 
level  in  the  canal  is  half  a  foot  below  their  ends.  In  canals  with 
6J  feet  depth  of  water  the  following  dimensions  have  been  used 
for  the  bars:  lower  end  \  foot  broad  by  \  of  a  foot  deep;  upper 
end  J  foot  broad  by  j  of  a  foot.  They  are  supported  on  12  -f  12 
inch  beams,  and  are  placed  such  distance  apart  that  18  go  into 
one  lo-foot  bay. 

According  to  the  experience  had  in  India  vertical  falls  ter- 
minating in  a  water-cushion  and  having  gratings  above  them  are 
the  best  form  that  has  yet  been  devised,  the  erosive  action  being 
diminished  to  a  minimum. 
17 


258 


FALLS    AND   DRAINAGE   WORKS 


.JL- 


GRATINGS    TO   RETARD    VELOCITY   OF   APPROACH 


259 


Such  a  fall  is  illustrated  in  the  standard  ic-foot  drop  built  by 
the  Reclamation  Service  on  the  Uncompahgre  canal,  Col.  (Fig. 
85).  The  canal  banks  and  bed  are  lined  with  concrete  for  a 
distance  of  20  feet  above  and  22  feet  below  the  fall  to  prevent 


FIG.  86.— Typical  ro-foot  Drop  with  Grating,  South  Canal,   Uncompahgre  Canal, 

Colorado. 

erosion,  tapering  in  thickness  from  6  to  12  inches.  The  effective 
height  of  drops  is  10  feet  but  the  total  height  of  fall  is  15  feet  6 
inches  to  a  water-cushion  20  feet  in  length  and  divided  trans- 


260 


FALLS   AND    DRAINAGE   WORKS 


versely  half  way  by  a  concrete  wall  10  feet  in  height  to  support  the 
grating.  This  wall  is  pierced  by  two  semicircular  openings  7 
feet  5  inches  in  height  and  9  feet  10  inches  in  width  to  give  free 
movement  of  the  water  (Fig.  86).  The  grating  is  of  40-pound 
rails  spaced  8  inches  between  centers,  slightly  inclined  up-stream, 
the  lowest  edge  being  6  feet  10  inches  above  the  floor  of  the 


!      .  „ : ,  Top  of  bank 


'JTop  of  bank 


Bottom  width  of  canal *   Riprap  canal  for      |^Top  of  bank 

varying  distances 


ELEVATION 
FIG.  87.— Notch  Fall,  Interstate  Canal,  Nebraska-Wyoming. 

fall.  This  latter  is  i  foot  6  inches  in  thickness  and  is  reinforced 
with  1 6-pound  rails  spaced  24  inches  centers  both  ways,  their 
ends  being  turned  up  2  feet  into  the  concrete  walls. 

224.  Notched  Fall  Crest. — Great  advantages  have  been  found 
in  India  in  adopting  a  notched  form  of  canal  fall,  which  practice 
has  shown  overcomes  almost  wholly  the  difficulties  of  excessive 


NOTCHED    FALL   CREST 


26l 


CROSS  SECTION 
FIG.  88.— Notch  Fall,  Chenab  Canal,  India. 


262 


FALLS    AND    DRAINAGE   WORKS 


velocity  and  erosive  action  below  the  fall.  Notched  falls  have  re- 
cently been  adopted  by  the  Reclamation  Service  as  standard  on  the 
Interstate  Canal,  North  Platte  project  (Fig.  87).  The  breast-wall 
or  crest  of  the  fall  is  cut  away  into  a  number  of  notches,  the  base 
of  which  are  at  a  level  with  the  canal-bed,  the  crest  of  the  breast- 
wall  being  above  full-supply  level  (Fig.  88).  At  the  foot  of  each 


FIG.  89. — Cross-section  of  Fall,  Bear  River  Canal. 

notch  is  a  lip  projecting  beyond  the  outer  face  of  the  breast- wall, 
which  has  an  influence  in  retarding  the  stream  and  determining 
the  form  of  the  lower  face  of  the  falling  water.  The  notches 
are  all  so  designed  as  to  discharge  at  any  given  level  the  same 
amount  of  water  as  the  canal  above  carries  at  that  level,  so  that 


VERTICAL    FALL   OF   WOOD 


263 


there  is  approximately  no  increase  in  velocity  in  the  canal  as 
the  water  approaches  the  fall,  while  a  uniform  depth  and  flow 
are  maintained.  The  water  flows  from  the  notches  in  a  fanlike 
shape,  and  meets  the  water  surface  below  in  a  steady  stream, 
which  contrasts  favorably  with  the  violent  ebullitions  which  accom- 
pany clear  overflows.  The  action  on  the  banks  of  canals  below 
the  falls  is  very  slight,  and  permits  of  the  wings  being  of  but  mod- 
erate length.  Mr.  R.  B.  Buckley  states  there  is  no  question  of 
the  superiority  of  this  over  all  other  forms  of  falls  where  it  can  be 
adopted.  The  form  of  the  basin  below  the  fall  is  practically  that 


FIG.  90. — Timber  Drop,  Lower  Yellowstone  Laterals,  Montana. 

of  a  shallow  water-cushion,  it  being  widened  in  addition  to  check 
the  ebullition  of  the  water  and  reduce  it  to  a  steady  forward 
velocity. 

225.  Vertical  Fall  of  Wood. — On  the  Galloway  canal,  Cali- 
fornia, simple  flashboard  checks  are  used  for  the  falls.  These 
checks  are  inclined  at  a  slight  angle  to  the  vertical,  and  the  water 
drops  to  a  wooden  apron  resting  on  mudsills  and  protected  by 
sheet  piling  at  its  ends,  while  the  bank  is  protected  by  wings. 

On  the  Bear  River  canal,  Utah,  are  a  number  of  falls,  ranging 
from  4  to  12  feet  in  height  (Fig.  89).  In  these  the  flooring  above 
and  below  the  apron  slopes  down  into  the  bed  of  the  canal  to 


264 


FALLS    AND   DRAINAGE   WORKS 


prevent  percolation.  Wooden  falls  on  the  Lower  Yellowstone 
canal  laterals,  like  nearly  all  others  built  by  the  Reclamation 
Service,  are  when  founded  on  piles,  protected  above  and  below 
by  shallow  sheet  piling,  and  have  water-cushions.  The  floors  of 
these  falls  above  the  drop  and  below  the  water-cushion  are 
covered  to  a  depth  of  about  afoot  with  gravel  (Fig.  90). 

226.  Masonry  Falls. — In  all  the  falls  in  India  masonry  work 
alone  is  used.  These  falls  have  sometimes  simple  vertical  drops, 
at  others  they  terminate  in  water-cushions  (Fig.  90).  In  the  larger 
falls  of  the  Reclamation  Service  reinforced  concrete  is  used,  wood 
being  adopted  only  for  small  drops  on  laterals.  Nearly  all  have 


FIG.  91. — Concrete  Fall  with  Water  Cushion,  Truckee-Carson  Canal,  Nevada. 

water-cushions.  It  is  customary  in  the  case  of  wide  canals  to 
divide  the  falls  into  bays  of  10  feet  each,  or  thereabouts,  by 
means  of  vertical  partitions  in  order  to  prevent  scour  and  back 
eddy  and  keep  the  water  moving  in  a  direct  course.  By  this 
means  each  may  be  separately  closed  and  repaired  if  necessary. 
An  interesting  series  of  two  falls  terminating  in  water-cushions 
on  the  Agra  canal  is  shown  in  cross-section  in  Fig.  92. 

227.  Wooden  Rapids  or  Chutes. — A  notable  wooden  rapid 
is  the  "Big  Drop"  on  the  Grand  River  canal  in  Colorado.  The 
canal  above  the  rapid  is  30  feet  wide  and  4  feet  deep,  and  is  nar- 
rowed down  at  the  head  of  an  inclined  flume  which  forms  the 


266  FALLS    AND   DRAINAGE   WORKS 

rapid  to  a  cross-section  of  5  by  4  feet.  The  flume  descends  with 
a  total  fall  of  35  feet  in  a  length  of  125  feet  (Fig.  93),  the  water 
being  discharged  against  a  solid  bulkhead  of  timbers  which  throws 
it  back  into  a  wooden  penstock.  From  this  it  escapes  over  a  riffled 
floor  1 6  feet  in  length,  beyond  which  is  an  additional  flooring  16 
feet  in  length,  whence  it  emerges  in  the  open  canal. 

Similar  wooden  chutes,  but  smaller,  with  falls  of  but  6  to  9 
feet,  have  been  built  on  laterals  of  the  Buford-Trenton  canals, 
North  Dakota,  by  the  Reclamation  Service.  In  these  the  drop 
terminates  in  a  wooden  box  forming  a  water-cushion. 

228.  Masonry  Rapids. — On  the  Bari  Doab  canal  in  India 
rapids  paved  with  loose  bowlders  have  been  used  with  great  suc- 
cess.    The  floors  of  these  rapids  (PL  XIV)  are  confined  between 
low  masonry  walls  so  as  to  prevent  the  movement  of  the  loose 
bowlders,  and  the  banks  are  protected  by  masonry  wings.     Bowl- 
ders form  a  better  material  for  the  flooring  of  a  rapid  than  does 
brickwork,  which  could  not  safely  be  used  with  velocities  exceed- 
ing 10  feet  per  second.     The  bowlder  floors  are  grouted  in  mortar 
and  will  safely  withstand  a  velocity  of  15  feet  per  second.     The 
tail  walls  of  these  rapids  are  peculiarly  curved  in  order  to  turn 
back  the  current  and  protect  the  canal  banks  from  the  direct 
action  of  the  water. 

On  the  Okanogan  project  of  the  Reclamation  Service,  Wash- 
ington, is  a  reinforced  concrete  rapid  or  chute  of  quite  abrupt 
slope.  The  height  of  fall  is  15  feet  in  a  horizontal  distance  of 
20  feet,  to  a  water-cushion  9  feet  long  by  5  feet  9  inches  deep 

(Fig.  94)- 

229.  Drainage  Works. — Where  the  diversion  line  of  a  canal 
is  carried  around  the  sides  of  hills  or  sloping  ground,  great  difficul- 
ties are  sometimes  encountered  in  passing  side  drainage.     The 
higher  the  canal  heads  up  on  a  stream  the  more  liable  is  it  to 
encounter  cross  drainage.     On  low  slopes  much  may  be  done  by 
diverting  the  watercourses  by  cuts  emptying  into  natural  drain- 
age lines.     When  this  cannot  be  done  it  may  be  passed  in  one  of 
the  following  ways : 

1.  By  drainage  diversion; 

2.  Inlet  dam; 


DRAINAGE    WORKS 


267 


268  FALLS   AND   DRAINAGE   WORKS 

3.  Level  crossing; 

4.  Flume  or  aqueduct; 

5.  Superpassage ; 

6.  Culvert  or  inverted  siphon. 

230.  Drainage  Cuts. — An   instructive  example   of  diversion 
by  means  of  a  drainage  cut  is  the  case  of  the  Chuhi  torrent  on  the 
Bari  Doab  canal  in  India.     This  torrent  had  two  outlets,  one  run- 
ning into  the  Beas  and  the  other  into  the  Ravi  River  just  above 
the  canal  crossing.     The  latter  was  embarked  close  to  the  bifur- 
cation by  a  bowlder  dam,  and  by  this  means  the  water  was  forced 
down  the  Beas  and  the  expense  of  crossing  the  canal  saved.     On 
the  Betwa  canal  in  India  is  another  interesting  diversion  cut. 
The  first  six  miles  of  this  line  are  protected  by  a  drainage  channel 
15  feet  wide  at  the  bottom  and  6  feet  deep,  which  runs  parallel  to 
the  canal  and  catches  the  minor  drainage  from  small  streams, 
which  it  discharges  into  the  Betwa  River  above  the  point  of  diver- 
sion of  the  canal. 

231.  Inlet  Dams. — Where  the  drainage  encountered  is  inter- 
mittent and  its  volume  is  small  relatively  to  that  of  the  canal, 
much  expensive  construction  may  be  saved  by  admitting  the  water 
directly  into  the  canal  and  permitting  it  to  be  discharged  through 
the  first  wasteway  on  its  line.     If  the  canal  crosses  a  depression  on 
a  hillside,  a  heavy  bank  will  of  necessity  be  built  on  its  lower 
side  to  keep  its  level  at  the  desired  height.     The  result  will  be  to 
back  the  water  up  the  drainage  depression,  thus  causing  waste, 
as  the  area  of  surface  exposed  to  evaporation  and  seepage  is  in- 
creased.    In  such  a  case  an  inlet  dam  should  be  built  on  the 
upper  side  to  confine  the  canal  within  reasonable  limits. 

Inlet  dams  may  be  of  wood,  masonry,  or  loose  stone.  If  the 
depth  of  the  canal  is  small  and  the  consequent  height  of  over- 
flow from  the  crest  of  the  dam  to  the  canal-bed  small,  a  wooden 
flume  may  be  laid  in  the  bed  of  the  canal  and  a  barrier  or 
dam  of  piles  and  sheet-piling  be  built  across  the  upper  side. 
In  a  short  time  the  sediment  carried  by  the  stream  will  fill  in 
behind  the  dam  to  a  level  with  its  crest  and  the  water  will 
simply  fall  over  it  onto  the  canal  floor.  The  inlet  dam  may  be 
made  as  a  loose  rock  retaining-wall,  when  the  bed  and  banks  of 


I 
1 


t 

P. 

c 


I 

I 


270  FALLS    AND    DRAINAGE   WORKS 

the  canal  below  and  opposite  should  be  riprapped  with  stone  to 
protect  them  from  erosion. 

In  case  the  drainage  torrent  is  of  some  magnitude  more  sub- 
stantial works  than  this  may  be  required,  and  it  may  be  necessary 
to  build  a  masonry  inlet  dam  and  perhaps  to  build  a  portion  of 
the  canal  channel  of  masonry,  revetting  the  opposite  bank  with 
loose  stone.  At  the  crossing  of  Reno  Coulee  by  the  Lower  Yellow- 
stone canal,  the  Reclamation  Service  has  constructed  an  inlet 
consisting  of  a  heavy  earth  embankment  set  back  25  feet  from 
the  canal  on  the  up-stream  slope.  In  this  the  inlet  heads  in  a 
masonry  retaining  wall  and  consists  of  a  terra-cotta  pipe  2  feet  in 
diameter  69  feet  long  with  a  fall  of  12  feet.  It  is  supported  at  in- 
tervals of  20  feet  by  concrete  walls  or  collars  6  ft.  square  and  18 
inches  in  thickness.  (Fig.  95.)  At  the  point  where  the  inlet  pipe 
discharges  into  the  canal  the  latter  is  paved  with  12  inches  of  con- 
crete, and  the  opposite  slope  of  the  canal-bed  for  a  short  distance 
above  and  below  are  paved  with  riprap  laid  in  cement  and 
grouted. 

232.  Level  Crossings. — When  the  discharge  of  the  drainage 
channel  is  large  and  it  is  encountered  at  the  same  level  as  the 
canal,  it  may  be  passed  over,  under,  or  through  the  latter.  In 
the  latter  case  the  water  is  admitted  by  an  inlet  dam  on  one  side 
and  discharged  through  a  wasteway  in  the  opposite  bank.  The 
discharge  capacity  of  the  latter  must  be  ample  to  pass  the  great- 
est flood  volume  likely  to  enter,  and  a  set  of  regulating  gates  must 
be  placed  in  the  canal  immediately  below  the  escape  in  order  that 
only  the  proper  amount  of  water  may  be  permitted  to  pass  down 
the  canal.  The  inlet  dam  must  be  constructed  as  described  in 
Article  231,  while  the  wasteway  and  gates  should  be  built  of  the 
usual  pattern. 

On  the  line  of  the  Turlock  canal  in  California  are  several  level 
crossings  of  peculiar  design,  built  where  the  canal  skirts  steep 
sidehill  slopes,  causing  the  embankment  on  the  lower  side  to 
become  practically  a  high  earthen  dam.  The  top  of  the  bank  is 
made  a  little  higher,  firmer,  and  wider  than  elsewhere  along  the 
canal  line,  and  in  the  case  of  two  of  these  drainage  crossings  no 
inlet  dam  has  been  constructed.  As  a  result  the  water  is  retained 


LEVEL   CROSSINGS 


271 


on  the  upper  side  of  the  canal  as  in  a  large  reservoir.  With  a  new 
canal  this  has  no  great  disadvantage,  as  such  construction  saves 
considerable  expense  in  the  beginning,  while  in  the  course  of  a  few 
years,  and  by  the  time  the  canal  water  becomes  valuable,  this 
reservoir  will  have  silted  up  and  the  canal  can  then  be  confined 
between  proper  limits.  These  earthen  drainage  dams  are  of  con- 
siderable height,  one  23  feet  and  the  other  40  feet  high,  and  in 
them  are  constructed  wasteways,  for  the  discharge  of  surplus 
waters. 

The  most  interesting  level  crossing  is  that  of  the  Rutmoo 


FIG.  96. — Plan  of  Rutmoo  Crossing,  Ganges  Canal,  India. 

torrent  on  the  Ganges  canal  in  India.  This  consists  of  a  simple 
inlet  at  the  torrent  entrance;  of  a  masonry  outlet  dam;  of  an 
escape  regulator  in  the  opposite  canal  bank;  and  of  a  regulating 
bridge  across  the  canal  channel  just  below  the  inlet  (Fig.  96). 
The  escape  dam  consists  of  47  sluiceways,  each  10  feet  wide,  with 
their  sills  flush  with  the  canal-bed  and  flanked  on  either  side  with 
overfalls  of  the  same  width  with  their  sills  6  feet  higher,  while  on 
the  extreme  flanks  are  platforms  10  feet  above  the  canal-bed. 


272  FALLS    AND    DRAINAGE    WORKS 

The  closing  and  opening  of  these  sluiceways  is  accomplished  by 
means  of  small  flashboards  fitting  into  grooves. 

233.  Flumes. — Where  drainage  encountered  is  at  a  lower 
level  than  the  bed  of  the  canal,  it  may  most  conveniently  be  passed 
under  the  latter,  which  crosses  over  it  in  a  flume.  Care  must  be 
taken  to  study  the  discharge  of  the  stream  crossed  in  order  that 
the  waterway  under  the  flume  may  be  made  ample  to  pass  the 
largest  flood  which  may  occur.  *  The  foundations  of  the  flume 
must  be  substantial,  'and  the  area  of  waterway  must  not  be  greatly 
impeded;  otherwise  the  velocity  in  the  drainage  channel  will  be 
so  great  as  to  cause  scour  of  its  bed  and  perhaps  the  destruction 
of  the  work.  :Care  must  be  exercised  in  connecting  the  ends  of 
the  flume  with  the  canal  banks  on  either  side  that  leakage  may 
not  occur  at  these  points. 

If  the  flume  is  built  across  a  depression,  expense  in  construc- 
tion is  usually  saved  by  limiting  the  length  of  the  structure  as 
much  as  possible.  This  is  done  by  making  its  approaches  on 
either  side  of  earth  embankment,  on  which  the  canal  is  carried. 
This  must  be  carefully  constructed  and  of  ample  width  that  it 
may  not  settle  greatly  or  be  washed  away,  and  it  must  be  faced 
with  abutments  and  wing  walls  at  its  junction  with  the  flume  to 
protect  the  latter  against  erosion.  That  the  dimensions  of  the 
flume  may  be  as  small  as  possible,  its  cross-section  is  generally 
diminished  and  it  is  given  a  slightly  greater  slope  than  the  canal 
at  either  end  to  enable  it  to  carry  the  required  volume. 

A  satisfactory  method  of  connecting  wooden  flumes  with  canal 
banks  consists  in  building  a  low  vertical  drop  of  2  to  4  feet  in  the 
flume  at  its  junction  with  the  earth  at  either  end,  and  then  filling 
up  to  the  level  of  the  canal  and  flume-gate  with  earth.  At  either 
end  of  the  drop,  against  the  earth  embankment  and  at  the  end  of 
the  flume  proper,  is  placed  sheet-piling,  while  the  earth  is  care- 
fully tamped  back  of  and  about  the  drop.  Another  plan  em- 
ployed with  satisfaction,  but  more  expensive  of  construction,  is  to 
build  out  at  the  end  of  the  flume  a  couple  of  parallel  rows  of  sheet- 
piling  at  right  angles  to  the  line  of  the  flume  and  canal,  and  still 
another  row  meeting  this  at  the  junction  with  the  flume  is  run 
out  at  45°,  thus  enclosing  an  angle  in  the  canal  bank  between  two 


274  FALLS    AND    DRAINAGE   WORKS 

rows  of  sheet-piling  filled  in  with  earth.  Another  way  of  making 
the  connection,  in  conjunction  with  one  of  the  methods  above 
described,  is  that  of  putting  in  an  inclined  drop  or  apron  running 
into  the  canal-bed,  with  sheet-piling  at  either  end.  Be  the  means 
employed  what  they  may,  the  greatest  care  must  always  be  ex- 
ercised in  making  the  connection  of  flume  ends  with  earth. 

234.  Sidehill  Flumes. — The  simplest  form  of  wooden  flume 
is  what  is  generally  known  as  a  bench  flume,  built  on  a  steep  side- 
hill  to  save  the  cost  of  canal  excavation.     Such  flumes  are  com- 
mon in  the  West,  notable  examples  being  the  bench  flume  on  the 
Highline  canal  in  Colorado  (PL  XV),  the  great  San  Diego  flume 
in  California.     The  former  is  a  little  over  half  a  mile  in  length. 
It  is  25  feet  wide  and  7  deep,  its  grade  being  5^  feet  per  mile  and 
its  discharge  1184  second-feet.     The  San  Diego  flume  was  built 
chiefly  to  give  the  canal  a  more  permanent  waterway  than  earth 
and  one  less  liable  to  the  losses  of  evaporation  and  absorption. 
In  this  case  fluming  is  employed  for  the  entire  length  of  the  canal, 
which  is  36  miles.     The  Santa  Ana  flume  was  built  for  similar 
reasons,  and  also  because  the  rocky  canyon  wall  on  which  it  is 
aligned  is  in  places  too  steep  to  permit  of  excavation  or  other  form 
of  channel  within  reasonable  limits  of  expense. 

Such  structures  should  never  be  built  on  embankments ;  they 
should  rest  everywhere  on  excavated  material  or  trestles  to  avoid 
the  danger  of  subsidence  and  consequent  destruction.  This 
excavated  bench  should  be  several  feet  wider  than  the  flume,  in 
order  to  give  a  place  on  which  loose  rock  from  the  sidehills  may 
lodge  without  injury  to  the  structure,  and  the  flume  itself  should 
rest  on  a  permanent  foundation  of  mudsills  or  posts. 

235.  Construction  of  Flumes. — The  boxing  of  flumes  is  gen- 
erally of  three  types : 

1.  The  floor  may  be  built  directly  on  stringers  and  the  plank- 
ing be  laid  at  right  angles  with  the  current  of  the  stream. 

2.  The  floor  beams  may  be  laid  on  stringers  braced  at  inter- 
vals calculated  to  bear  the  water  pressure;    the  standards  and 
floor  beams  being  boxed  in  and  bolted  to  the  outside  braces,  the 
whole  forming  the  foundation  for  putting  on  the  inside  sheeting 
or  boxing. 


STAVE    AND    BINDER    FLUMES 


275 


3.  The  floor  beams  and  stringers  may  be  formed  in  cross 
beams  yoked  to  receive  the  boxing. 

The  lumber  forming  the  boxing  of  the  flume  should  be  from 
ij  to  2\  inches  in  thickness,  according  to  the  dimensions  of  the 
flume.  It  should  be  of  good  grade  and  well  seasoned.  The 
best  practice  is  to  match  the  various  planks  together  either  by 
ship-lap  joints  or  driven  tongue-joints,  which,  if  shrinkage  occurs, 
should  be  calked  with  oakum. 

An  excellent  example  of  bench  flume  is  that  of  the  San  Diego 
Flume  Company  (Fig.  97),  which  is  6  feet  wide  in  the  clear  and 


FIG.  97. — Cross-section  of  San  Diego  Flume,  California. 

4  feet  deep;  the  bottom  and  sides  are  planked  with  2-inch  red- 
wood, and  the  boxing  rests  on  transverse  sills  of  2 -inch  planking 
laid  4  feet  apart,  and  upon  these  are  4  by  6  longitudinal  stringers, 
above  which  is  constructed  the  framework  of  the  flume,  consisting 
of  4  by  4  scantling  placed  at  intervals  of  4  feet  and  braced  by 
diagonal  uprights  2  by  4  inches  and  3  feet  in  length.  Another 
and  even  better  type  of  flume  is  that  shown  in  Fig.  98,  being  the 
standard  type  of  wooden  flume  and  trestle  adopted  by  the  Re- 
clamation Service. 

236.  Stave  and  Binder  Flumes. — This  type  of  structure  is 
curved  in  cross-section,  and,  as  indicated  by  the  title,  is  like  the 
lower  half  of  a  wooden  water-pipe  (Article  277).  It  consists  of 
wooden  staves  bound  and  held  together  in  a  rounded  bottom  by 
iron  and  steel  ribs  and  binding-rods,  acting  in  conjunction  with 
wooden  yokes  or  ties  across  the  top  (Fig.  98).  In  its  simplest 


276 


FALLS    AND    DRAINAGE   WORKS 


form  this  flume  is  semicircular,  with  the  top  edges  braced  apart 
by  the  stiff  yoke  or  cross-head,  so  that  there  is  no  tendency  of  the 
shell  to  buckle  inward.  As  developed  on  the  Santa  Ana  canal, 
the  sides  are  formed  of  broader  boards  which  are  carried  up 
vertically  in  a  line  tangent  to  the  ends  of  the  bottom  half -circle 
and  to  the  desired  height.  Upon  applying  the  binding  com- 
pression on  this  form  there  is  a  tendency  to  buckle  inward,  which 
is  obviated  by  stiff  ribs  made  to  serve  as  binders  and  introduced 
at  intervals  in  the  shell.  This  flume  has  not  been  successful,  for, 


FIG.  98. — Cross-section  of  Stave  and  Binder  Flume,  Santa  Ana  Canal. 

if  not  well  filled  with  water,  cracks  open  and  sand  gets  in  these, 
making  it  impossible  to  cinch  them  up  water-tight  again. 

237.  Flume  Trestles. — Where  the  flume  crosses  a  depression  it 
rests  on  trestles.    (Fig.  99.)   These  are  constructed  as  are  the  ordi- 
nary trestles  on  railway  lines.     Where  the  trestle  rests   on   dry 
ground  it  may  be  founded  on  mudsills,  on  short  posts  let  into  the 
soil,  or  on  concrete  blocks,  but  where  it  crosses  drainage  channels 
it  must  be  substantially  founded  on  cribs,  piling,  or  concrete. 
The  superstructure  of  a  flume  crossing  a  drainage  line  is  similar  to 
that  of  bench  flumes. 

238.  Iron  Aqueducts. — The  chief  difficulty   encountered   in 
constructing  long  aqueducts  of  iron  has  been  the  expansion  and 
contraction  of  the  metal,  though  in  practice  it  has  been  found  that 


IRON    AQUEDUCTS 


277 


the  metal  of  the  structure  has  approximately  the  same  tempera- 
ture as  that  of  the  water,  and  as  this  is  somewhat  uniform  but 
little  change  takes  place  in  the  dimensions  of  the  aqueduct.  On 
the  Bear  River  canal  in  Utah  are  two  aqueducts,  one  of  which 
consists  of  a  wooden  flume  resting  on  iron  trestles  founded  on 
masonry  columns.  The  other  is  a  simple  iron  aqueduct  resting 
on  iron  trestles.  The  floor  of  this  is  37  feet  above  the  bed  of  the 


*'C.to  C.- 


-4'c.to  C.- 


DETAIL  OF  WEDGE 
AND  YOKE 


ELEVATION 
FIG.  99.— Standard  Timber  Flume  and  Trestle,  U.  S.  Reclamation  Service. 


stream,  and  its  length  is  130  feet  (Fig.  100),  disposed  in  three 
bents,  the  center  span  of  which  is  60  feet  long,  the  other  two  being 
respectively  25  and  45  feet  long.  This  aqueduct  is  essentially  a 
plate-girder  bridge  resting  on  iron  columns  and  founded  on  iron 
cylinders  rilled  with  concrete  and  resting  on  piles.  The  plate 
girders  forming  the  sides  of  the  aqueduct  are  5 J  feet  in  depth,  the 
available  depth  of  water  being  4  feet.  The  sides  of  the  girder  are 
braced  by  vertical  angle-iron  riveted  to  it  every  5  feet  apart,  while 


278 


FALLS    AND    DRAINAGE    WORKS 


the  top  is  cross-braced  by  similar  angle-iron.  These  angle-irons 
vary  between  3  and  4  inches  in  width,  while  the  web  of  the  sides 
of  the  aqueduct  consists  of  f -inch  iron. 

On  the  Henares  canal  in  Spain  is  an  iron  aqueduct  over  the 
Majanar  torrent.     This  aqueduct  is  70  feet  long  with  a  clear  span 


l   l   l  l    »   l    l        ULJ 


FIG.  100. — Elevation  and  Cross-section  of  Iron  Flume  on  Corinne  Branch, 
Bear  River  Canal,  Utah. 

of  62  feet.  Its  waterway  is  10.17  feet  wide>  its  capacity  being 
177  second-feet.  The  sides  are  composed  of  box  girders  6.2  feet 
deep  (Fig.  101),  and  each  girder  is  calculated  to  bear  200  tons  or 
the  entire  structure  to  carry  400  tons.  To  prevent  leakage  the 
ends  of  the  aqueduct  rest  on  stone  templates,  and  4  inches  from 


MASONRY   AQUEDUCTS 


279 


each  end  is  a  pillow  composed  of  long  strips  of  felt  carpet  9  inches 
wide  and  soaked  in  tallow,  which  is  let  into  the  stone  below  the 
aqueduct.  This  presses  on  it  with  its  full  weight,  thus  making  a 
water-tight  joint.  In  addition  to  this  lead  flushing  is  riveted  to 
the  aqueduct  and  let  into  a  recess  of  the  stone  abutments.  This 
recess  is  1 2  inches  deep  and  4  inches  wide,  and  around  it  is  poured, 


Half  Utvation  of  Aqueduct 


FIG.  101. — Aqueduct,  Henares  Canal,  Spain. 

hot,  a  mixture  of  tar,  pitch,  and  sand,  which  allows  slight  play 
during  its  expansion  and  contraction  and  yet  is  water-tight. 

239.  Masonry  Aqueducts. — In  general  design  masonry  aque- 
ducts are  planned  and  constructed  much  as  are  those  of  wood  or 
iron.  One  of  the  greatest  structures  of  this  kind  is  the  Solani 
aqueduct  on  the  Ganges  canal  in  India  (PI.  XVI).  This  consists 
of  an  earth  embankment  approach  or  terre  plein  2  J  miles  in  length 
across  the  Solani  valley,  its  greatest  height  being  24  feet.  This 
embankment  is  350  feet  wide  at  the  base  and  290  feet  wide  on  top, 
and  on  this  the  canal  banks  are  formed,  the  width  of  the  banks 


MASONRY   AQUEDUCTS 


28l 


being  30  feet  on  top  and  the  bed  width  of  the  canal  150  feet.  The 
aqueduct  is  920  feet  in  length  with  a  clear  water  space  between 
piers  of  750  feet,  disposed  in  fifteen  spans  of  50  feet  each.  The 


FIG.  102. — Elevation  and  Cross-section  of  Nadrai  Aqueduct,  Lower  Ganges 

Canal,  India. 

breadth  of  each  arch  parallel  to  the  channel  of  the  river  is  192  feet 
and  its  thickness  5  feet.  The  greatest  height  of  the  aqueduct 
above  the  river  valley  is  38  feet,  and  the  walls  of  the  waterway 


282 


FALLS    AND    DRAINAGE   WORKS 


are  8  feet  thick  and  12  feet  deep.     This  structure  is  founded  on 
masonry  piers  resting  on  wells  sunk  20  feet  in  the  river-bed. 

Perhaps  the  most  magnificent  aqueduct  ever  built  is  that  car- 
rying the  Lower  Ganges  canal  across  the  Kali  Nadi  torrent  in 


Span  varies  from  U  to  30 


Span 

710     24 

10'  s'o 

IS1  <j'o"  28'  9'4" 


Bottom  longitudinals 
to  be  bent  down  j 


Lower  girder  bare 
continuous 


PLAN  OF  INLET 
May  be  used  for  outlet  when  "* 
desirable  .| 

.        Bars  In  Floor  *• « 
12  c.  to  o.  both  way 
placed  in  center 

SECTION 

/Method  of  bonding 
flume  to  inlet 


LONGITUDINAL  SECTION  OF  INLET 


PLAN  OF  COLUMN  BASE 


2o"x7.'o" 

6=6'        2'3*i9'o' 
=8',       2'6'xll'.0 
6  =  10        2f9  x  13  0' 
6  =  12       3'0  "x  150* 

SCALE  OF  FEET 


FIG.  103. — Standard  Reinforced  Concrete  'Flume,  Reclamation  Service. 

India  (Fig.  102).  The  present  structure  was  built  to  replace 
another  of  similar  design  which  was  destroyed  by  a  flood  which 
the  waterway  under  the  aqueduct  was  too  small  to  pass.  This 
was  calculated  to  discharge  30,000  second-feet,  whereas  the  flood 


REINFORCED    CONCRETE   FLUMES   AND   AQUEDUCTS      283 


4  'Square 


which  destroyed  it  amounted  to  135,000  second-feet  in  volume. 
The  present  aqueduct  consists  of  fifteen  masonry  spans  each  50 
feet  in  width  and  supported  on  masonry  wells  sunk  to  a  maximum 
depth  of  50  feet.     Under  the 
aqueduct  is  built  up  a  con- 
crete floor  5  feet  in  thickness 
to   prevent  erosion    and    de- 
struction of  the  foundation. 

240.  Reinforced  Concrete 
Flumes  and  Aqueducts.  —  In 
the  construction  of  flumes  and 
aqueducts  the  Reclamation 
Service  has  made  almost  ex- 
clusive use  of  reinforced  con- 
crete, as  it  has  in  nearly  all 
other  structures.  There  is 
quite  a  variety  in  the  design 
of  these  works,  though  for 
flumes  of  moderate  size  the 
design  of  flumes  and  of  the 
supporting  trestles  over  de- 
pressions follows  closely  that 
of  wooden  structures  of  like 
kind.  In  Fig.  103  are  illus- 
trated the  details  of  standard 
reinforced  concrete  flumes 
of  moderate  capacity.  The 

depth  nearly  equals  the  width,      FIG.    104.—  Circular  Reinforced  Concrete 


H'Joint 


fj1™   and    Trestle>    Tieton    Cana1' 

Washington. 


and  the    thickness    of   walls 

and    manner    of    reinforcing 

are  such  that  no  cross-bracing  is  necessary  to  hold  the  sides  in 

position. 

On  the  Tieton  project,  Washington,  a  flume  of  semicircular 
cross-section  is  also  used.  This  (Fig.  104)  has  thinner  walls  and 
these  are  therefore  cross-braced  with  4-inch  square  concrete 
beams  10  feet  long  and  reinforced  with  two  J-inch  steel  rods. 
The  shell  of  the  flume  154  inches  thick  reinforced  circumferentially 


284 


FALLS    AND    DRAINAGE    WORKS 


with  f-inch  steel  rods  spaced  4  inches  centers  and  each  ly 
long,  and  longitudinally  by  eighteen  J-inch  steel  rods  spaced  12 
inches  centers.  The  trestles  are  of  reinforced  concrete  cross- 
braced  with  steel  tie-rods.  The  concrete  posts  are  12  inches 
square  reinforced  with  four  J-inch  steel  rods  and  the  caps  and 
struts  are  6  by  12  inches  reinforced  with  two  J-inch  rods. 

On  the  Interstate  canal,  Nebraska,  is  a  reinforced  concrete 
aqueduct  206  feet  long  and  34  feet  wide  by  12  J  feet  deep  inside, 
which  is  carried  over  Spring  Canyon  on  a  massive  masonry  multi- 
arched  reinforced  concrete  bridge  (Figs.  105  to  107).  The  walls 


10 ;,p 


HALF  SECTION 


SCALE  OF  FEET 
10  20 


FIG.  105, — Half  Longitudinal  Section,  Reinforced  Concrete  Aqueduct,  Interstate 
Canal,  Nebraska-Wyoming. 

of  the  aqueduct  are  ioj  inches  thick  at  top  and  12 \  inches  at 
bottom,  and  heavily  reinforced  with  j-  to  i-inch  rods  as  shown. 
The  floor  is  24  inches  thick  and  is  reinforced  with  i-inch  steel 
rods  spaced  6  inches  centers  and  turned  up  two  feet  into  the 
walls.  The  tops  of  the  latter  are  cross-braced  every  1 1  feet  9 
inches  with  built-up  steel  lattice  beams  16  inches  deep  and  let  well 
into  and  firmly  bolted  into  the  concrete  walls. 

The  foundations  and  columns  of  the  supporting  bridge  are  of 
massive  concrete,  the  main  arches  being  reinforced  with  two  rows 
of  i-  to  i  i-inch  steel  rods  spaced  2  ft.  centers.  The  superimposed 
arches  are  reinforced  with  No.  10  gauge  4-inch  mesh  wire  fabric. 

241.  Superpassages. — Where  the  canal   is   at   a  lower  level 


SUPERPASSAGES 


than  the  drainage  channel,  a  superpassage  is  employed  to  carry 
the  latter  over  the  canal.  This  is  practically  an  aqueduct,  though 
there  are  some  elements  entering  into  its  design  which  are  different 
from  those  affecting  aqueducts.  The  volumes  of  streams  which 
are  to  be  carried  in  superpassages  are  variable,  at  times  they  may 
be  dry,  while  at  others  their  flood  discharges  may  be  enormous. 
No  provision  has  to  be  made  for  passing  flood  waters  under  the 
structure,  since  the  discharge  of  the  canal  beneath  it  is  fixed. 


Tin-  longitudinal  reinforcing  rods  of 
the  flume  are  to  t*  carried  5-uinto 


SCALE  OF  FEET 


7     8     fl     10 


FIG.  106. — Section  Through  Reinforced  Concrete  Aqueduct,  Interstate  Canal, 
Nebraska -Wyoming. 

On  the  other  hand,  the  water-way  of  the  superpassage  must  be 
made  amply  large  to  carry  the  greatest  flood  which  may  occur  in 
the  stream,  and  much  care  must  be  taken  in  joining  the  super- 
passage  to  the  stream-bed  above  and  below  to  prevent  injury  by 
the  violent  action  of  the  flood  waters. 

No  instance  can  be  cited  where  superpassages  have  been  con- 
structed in  the  United  States.  In  nearly  every  case  where  these 
would  have  been  required  the  stream  has  been  taken  under  the 
canal  in  an  inverted  siphon.  In  India,  however,  superpassages 
have  frequently  been  used  on  the  canals  in  preference  to  inverted 
siphons  chiefly  because  of  the  requirements  of  navigation. 

It  would  probably  be  a  dangerous  experiment  to  attempt  to 


286 


FALLS   AND    DRAINAGE    WORKS 


construct  a  superpassage  of  wood,  because  it  would  be  so  con- 
stantly subjected  to  alternate  drying  and  wetting,  according  as 
there  was  or  was  not  water  flowing  in  the  stream,  that  it  would 
soon  decay.  A  small  iron  superpassage  has  been  constructed 
across  the  Agra  canal  in  India  which  is  99  feet  long,  30  wide,  10 
feet  deep,  of  boiler-iron  strongly  cross-braced.  It  is  supported  on 
masonry  piers  and  has  a  steep  slope  giving  a  high  velocity.  The 
connection  between  its  ends  and  the  abutments  is  made  by  means 
of  heavy  sheet  lead  to  accommodate  the  changes  due  to  expansion 


FIG.  107. — Reinforced  Concrete  Aqueduct,  Spring  Canyon,  Interstate  Canal, 
Nebraska-Wyoming. 

of  the  iron.  This  precaution  is  more  necessary  in  a  superpassage 
than  in  an  aqueduct,  as  it  is  more  subject  to  changes  of  tempera- 
ture when  empty. 

On  the  Ganges  canal  in  India  are  two  of  the  largest  super- 
passages  ever  constructed.  One  carries  the  Puthri  torrent  and 
the  other  the  Ranipur  torrent  over  the  canal.  The  discharge  of 
the  former  amounts  in  times  of  flood  to  as  much  as  15,000  second- 
feet  The  Ranipur  superpassage  (PL  XVII)  is  built  of  masonry 


PLATE  XVIII. — Idaho  Irrigation  Company's  Canal.     View  of  Wooden  Siphon  on 

Phyllis  Branch. 


CULVERTS   AND    INVERTED    SIPHONS 


289 


founded  on  wells,  and  its  flooring, 
which  is  given  a  steep  slope  in 
order  that  the  velocity  shall  pre- 
vent its  filling  up  with  sediment, 
is  3  feet  in  thickness  above  the 
crown  of  the  arches  and  is  bordered 
by  parapets  7  feet  wide  and  4  feet 
high.  The  flooring  and  parapets 
continue  inland  from  the  body  of 
the  work  a  distance  of  100  feet  on 
each  side,  the  latter  expanding 
outward  so  as  to  form  wings  to 
keep  the  water  within  bounds. 
The  superpassage  is  300  feet  long 
and  provides  a  water-way  195  feet 
wide  and  6  feet  deep. 

242.  Culverts  and  Inverted 
Siphons. — Where  the  canal  is  not 
used  for  purposes  of  navigation  and 
encounters  drainage  at  a  relatively 
low  level,  the  most  convenient  and 
usual  form  of  crossing  is  by  means 
of  inverted  siphons  or  culverts. 
Sometimes  the  canal  is  carried  in  a 
siphon  under  the  stream,  some- 
times the  stream  is  carried  in  a 
culvert  under  the  canal.  The  di- 
mensions of  the  culvert  or  siphon 
are  to  be  computed  by  means  of 
one  of  the  many  formulas  for  the 
flow  of  water  through  pipes  (Arts. 
273  to  275),  though  the  formula 
for  flow  through  open  channels 
may  also  be  used  in  some  cases 
(Art.  78).  Inverted  siphons,  or 
pressure-pipes  are  frequently  em- 
ployed in  crossing  deep  depressions 
19 


290 


FALLS    AND    DRAINAGE    WORKS 


CROSS  SECTION 


FIG.  109. — Soane  Canal,  India.     Cross-section  of  Kao  Nulla  Siphon-aqueduct. 


FIG.  no. — Sections  of  Sesia  Siphon,  Cavour  Canal,  Italy 


/ 

WOODEN   CULVERT 

in  place  of  flumes  on  high  trestles.  . 
This  method  is  most  satisfactory  in 
crossing  depressions  carrying  little 
drainage  water.  In  some  cases 
wrooden  pipe  (PL  XVIII),  in  others 
wrought-  or  cast-iron  or  reinforced 
concrete  pipes  are  used. 

243.  Wooden  Culvert. — An    ex- 
cellent example  of  a  small  work  of 
this  kind  is  the  wooden  culvert  on 
the   Del   Norte    canal    in  Colorado 
(Fig.    108).     This  consisted  of   two 
parallel  wooden  boxes,  each  4  feet 
6  inches  wide  by  3  feet  high,  sup- 
ported   on    piling  and  framed  and 
braced  with  6  by  8  scantling.     The 
bottom  and  sides  were  floored  with 
2-inch  plank,  while  the  top   which 
had  to  bear  the  weight  of  the  super- 
incumbent   earth    and    water,    was 
covered  with    6-inch    planking  laid 
crosswise.    This  culvert  was  recently 
washed  away  and  has  not  been  re- 
stored. 

244.  Inverted    Siphons    of    Ma- 
sonry.— An  interesting   structure  of 
this  kind  is  that  carrying  the  Kao 
torrent    under  the    Soane  canal    in 
India    (Fig.    109).     This    work    is 
built   of  the    most  substantial   ma- 
sonry, the  area  of  the  superstructure 
being  contracted  and  given  a  slightly 
increased  grade  to  carry  the  waters 
of  the  canal,  while  the  waters  of  the 
torrent   flow  over   a   masonry   floor 
which  is  depressed  a  few  feet. 

The  most  magnificent   masonry 


29I 


/ 


:,L- 


292 


FALLS   AND    DRAINAGE   WORKS 


siphon  ever  built  is  that  carrying  the  waters  of  the  Cavour 
canal  under  the  Sesia  River  in  Italy.  Its  total  length  is  878 
feet  and  it  consists  of  five  oval  orifices  (Fig.  no),  each  7.8 


feet  in  height  by  16.2  feet  in  width,  the  amount  of  depression 
of  the  water  surface  in  the  canal  being  7^  feet.  The  siphon 
consists  of  a  substantial  concrete  floor  or  foundation  nj  feet 
in  thickness  under  the  river-bed,  its  roof  forming  the  floor  of 


INVERTED    SIPHONS    OF    MASONRY 


293 


the  river  channel  and  being  about  3  feet  in  thickness.  Another 
large  siphon  is  that  on  the  Sirhind  canal  in  India  crossing  the 
Hurron  torrent.  The  total  length  of  this  is  212  feet,  and  it  con- 


PLATE  XIX  A. — Inlet  to  Rawhide  Siphon, Interstate  Canal,  Nebraska-Wyoming. 


PLATE  XIX  B. — Siphon  Crossing  Under  Rawhide  Creek,  Interstate  Canal, 
Nebraska-Wyoming. 

sists  of  two  openings  each  4  feet  high  by  15  feet  wide.  The 
water  drops  from  the  canal  almost  vertically  into  a  well,  the 
floor  of  which  is  on  a  level  with  the  floor  of  the  siphon,  while 


294 


FALLS    AND    DRAINAGE    WORKS 


at  its  exit  it  is  raised  again  to  the  level  of  the  outlet  canal  up 
an  incline  built  in  steps. 

245.  Reinforced  Concrete  Culverts. — On  nearly  every  canal 
of  the  Reclamation  Service  are  one  or  more  culverts  of  reinforced 
concrete,  this  material  and  mode  of  crossing  being  generally 
adopted.  Fig.  in  shows  a  longitudinal  and  cross-section  of  such 
a  culvert  built  for  passing  the  water  of  War  Dance  coulee  under 
the  Lower  Yellowstone  canal.  The  culvert  consists  of  two  rect- 
angular pipes  each  3  by  5  feet  with  1 2-inch  reinforced  concrete 


PART  LONGITUDINAL  SECTION 


Ji  R.S  C.to~C. 
66  Longitudinal 
Rods  y'i  tf 

FIG.  113. — Reinforced  Concrete  Twin  Siphon,  Dry  Spotted  Tail  Creek,  Interstate 
Canal,  Nebraska-Wyoming. 

walls.  At  entrance  and  exit  are  reinforced  concrete  bays  with 
paved  approaches.  At  intervals  along  the  culvert  are  heavy 
concrete  collars  to  prevent  travel  of  seepage  water  from  the 
canal. 

246.  Reinforced  Concrete  Siphons. — Like  the  culverts,  the 
siphons  built  by  the  Reclamation  Service  are  of  reinforced  con- 
crete. The  Lower  Yellowstone  canal  is  carried  under  Fox  Creek 
in  a  twin  siphon  of  sewer  or  egg-shaped  cross-section  (Fig.  112). 
At  entrance  and  exit  are  bays  lined  with  concrete  and  with  paved 
approaches.  Three  sets  of  concrete  collars  18  inches  thick  and  5 
feet  deep  are  at  either  end  to  prevent  seepage  and  below  these 
is  4j-inch  sheet  piling.  Each  pipe  is  of  9  inches  of  concrete  rein- 
forced circumferentially  with  bars  \  to  J  inches  square  and  15 


REINFORCED    CONCRETE    SIPHONS  295 

to  17  inches  centers,  while  longitudinal  bars  are  spaced  at  in- 
tervals of  about  1 8  inches.  In  the  siphon  is  a  blow-off  of  10 
inch  pipe  with  reducer  and  valve. 

On  the  Interstate  canal  of  the  North  Platte  project  arc  sev- 
eral siphons,  that  under  Rawhide  creek  being  shown  in  Pis.  XIX 
A  and  B,  and  cross  and  longitudinal  sections  of  that  under  Dry 
Spotted  Tail  creek  in  Fig.  113.  The  latter  is  a  twin  siphon  of 
rectangular  section  with  curved  invert.  The  walls  are  of  con- 
crete 10  to  12  inches  thick  and  are  reinforced  with  two  circum- 
ferential and  one  longitudinal  rows  of  J  inch  bars. 


•  CHAPTER  XIII 

DISTRIBUTARIES 

247.  Object  and  Types. — Distributaries  are  to  a  main  canal 
system  what  service  pipes  are  to  the  mains  in  city  water  service. 
The  minor  or  farm  ditches,  from  which  water  is  directly  applied 
to  the  crops,  should  never  be  diverted  from  the  main  canal  nor 
from  its  upper  branches.     It  is  desirable  to  have  as  few  openings 
in  the  bank  of  the  main  canal  as  possible,  so  as  to  reduce  to  a 
minimum  the  liability  of  accident.     The  water  is  drawn  at  proper 
interval  from  the  main  line  into  moderate-sized  branches  which 
are  so  arranged  as  to  command  the  greatest  area  of  land  and  to 
supply  the  laterals  and  farm  ditches  in  the  most  direct  manner. 
Wherever  water  has  not  a  high  intrinsic  value  it  is  conducted  to 
the  lands  in  open  distributaries  and  laterals.     Where,  however, 
its  value  is  relatively  high  it  is  desirable  to  reduce  the  losses  from 
absorption  and  evaporation  to  a  minimum.     In  such  cases  the 
laterals  consist  of  wooden  flumes  or  of  paved  or  masonry-lined 
earth  channels,  while  in  extreme  cases,  such  as  are  encountered 
in  Southern  California,  water  is  conducted  underground  to  the 
point  of  application  in  pipes,  and  is  applied  to  the  crops  from  these 
instead  of  being  flowed  over  the  surface.     By  such  methods  of 
handling  the  highest  possible  duty  is  obtained  .and  the  most 
effective  use  made  of  the  water  at  command. 

248.  Location  of  Distributaries. — Distribution  from  a  canal 
is  most  economically  effected  when  it  runs  along  the  summit  of  a 
ridge  so  that  it  can  supply  water  to  its  branches,  to  laterals  and  to 
private  channels  on  either  side.     In  the  case  of  main  canals  this 
location  can  be  made  only  in  occasional  instances ;  but  the  laterals 
taken  from  these  mains  should  be  made  to  conform  to  the  dividing 
lines  between  watercourses.     The  capacity  of  the  laterals  which 
then  traverse  the  separate  drainage  divides  is  proportioned  to 

296 


DESIGN    OF   DISTRIBUTARIES 


297 


the  duties  they  have  to  perform,  the  natural  bounding  streams 
limiting  the  area  they  have  to  irrigate. 

In  designing  a  distributary  system  too  little  care  and  attention 
are  ordinarily  paid  to  its  proper  location  and  survey;  yet  it  is  in 
the  distribution  and  handling  of  water  that  the  greatest  losses 
occur,  and  accordingly  it  is  there  that  the  greatest  care  should  be 
taken  in  its  transportation.  Careful  surveys  should  be  made  of 
the  area  to  be  traversed  by  the  distributaries,  as  described  in  Arti- 
cle 138  for  the  location  of  main  canals,  and  the  greatest  care 


FIG.  114. — Diagram  Illustrating  Distributary  System. 

should  be  taken  to  balance  cuts  and  fills  and  to  so  locate  the  laterals 
that  the  least  loss  of  water  shall  occur  from  percolation. 

In  Fig.  114  is  shown  an  ideal  distributary  system.  The  con- 
tour lines  and  drainage  courses  show  the  general  slope  and  lay 
of  the  country,  and  the  main  canal  and  its  branches  should  be 
run  down  the  divides  between  these  drainage  lines  as  indicated. 
Such  an  arrangement  enables  the  least  mileage  of  channels  to 
command  the  greatest  area  of  country  by  furnishing  water  to 
both  sides  of  its  line.  At  the  same  time  perfect  drainage  is  ob- 
tained by  the  water  flowing  in  both  directions  into  the  natural 
watercourses. 

249.  Design  of  Distributaries. — For  the  more  complete  and 
efficient  distribution  of  water  the  engineer  treats  laterals  as  of 


298 


DISTRIBUTARIES 


as  much  importance  as  the  mains  and  branches.  Attention  is 
devoted  to  the  character  of  the  soil  traversed,  to  the  alignment,  to 
the  safe  and  permanent  crossing  of  natural  drainage  lines,  and 
especially  to  so  maintaining  the  surface  of  the  canal  with  relation 
to  the  ground  as  to  command  the  largest  irrigable  area.  In  all 
well-designed  distributary  systems  the  capacity  of  the  channels 
is  exactly  proportioned  to  the  duty  to  be  performed,  the  cross- 


High  Lin* 

Pumping  Station 
Arrow] Creek  Crossing 
•5 


FIG.  115. — Distributary  System,  Huntley  Canal,  Montana. 

sectional  area  being  diminished  as  the  quantity  of  water  is  de- 
creased by  its  diversion  to  private  watercourses. 

The  lateral  should  be  taken  off  from  the  main  canal  as  near 
the  surface  of  the  latter  as  possible,  the  bed  of  the  lateral  not 
being  on  a  level  with  the  bed  of  the  canal,  bui;  placed  with  refer- 
ence to  the  full  supply  of  the  main  canal,  in  order  to  get  the  clearest 
water,  and  in  order  that  the  bed  of  the  lateral  may  be  kept  at  a 
high  level  and  admit  of  surface  irrigation  throughout  its  length. 
In  level  country  care  should  be  taken  in  designing  distributaries 


EFFICIENCY   OF    A    CANAL  2QQ 

that  the  natural  drainage  lines  into  which  they  tail  shall  be 
sufficiently  large  to  accommodate  any  flood  volume  it  may  be 
necessary  to  pour  into  them;  otherwise  the  stream  courses  may 
become  clogged  and  flood  the  surrounding  country.  On  many 
of  the  Reclamation  Service  projects  on  very  level  lands  (Fig.  1 15), 
the  laterals  for  convenience  follow  the  rectangular  boundaries  of 
the  public  land  subdivision. 

In  order  to  avoid  the  construction  of  costly  embankments  and 
to  insure  the  surface  of  the  water  being  above  that  of  the  country 
the  slope  of  the  lateral  should  be  made  as  nearly  parallel  as  possible 
to  that  of  the  land  it  traverses.  To  effect  this  alignment,  falls 
must  be  frequently  introduced,  and  to  dispose  of  storm-waters, 
wasteways  into  natural  drainage  lines  should  be  provided  at  least 
every  10  miles  in  the  course  of  the  lateral. 

250.  Efficiency  of  a  Canal. — According  to  Mr.  J.  S.  Beres- 
ford,  an  Indian  engineer,  we  may  look  upon  a  great  canal  system 
as  a  machine  composed  of  four  parts  and  calculate  its  efficiency 
in  the  same  way  as  that  of  a  steam-engine.  These  parts  are: 

1.  The  main  canal. 

2.  The  distributaries. 

3.  The  private  irrigating  channels. 

4.  The  cultivators  who  supply  the  water  to  the  soil. 

Each  cubic  foot  of  water  entering  the  canal  head  is  expended 
in  five  ways : 

1.  In  waste  by  absorption  and  evaporation  in  passing  from 
the  canal  head  to  the  distributary  head. 

2.  In  waste  from  the  same  causes  between  the  distributary 
head  and  the  head  of  the  private  channel. 

3.  In  waste  from  the  same  causes  in  passing  from  the  private 
channel  to  the  field  to  be  watered. 

4.  In  waste  by  the  cultivators  in  handling  the  water,  both  by 
causing  losses  from  evaporation  or  from  percolation  where  an 
unnecessary  amount  is  applied. 

5.  In  useful  irrigation  of  the  land. 

The  object  is  plainly  to  increase  the  last  item  by  the  reduction 
of  all  the  rest.  Calling  Dl  the  theoretic  duty  of  a  foot  of  water 
entering  the  canal  head,  we  have  the  actual  duty  of  the  canal. 


300  DISTRIBUTARIES 


.......     (i) 

where  Cme  represents  the  mean  efficiency  of  the  main  canal.  Now 
if  the  efficiency  of  water  entering  a  distributary  head  for  use  in 
watering  a  field  from  an  outlet  is  called  A,  the  duty  of  water  used 
in  this  field  will  be 

D  =  EXD>    ........     (2) 

and 

E  =  EdxEwxEc,   ......     (3) 

where  Ed  is  the  efficiency  of  the  distributary,  Ew  is  the  efficiency 
of  the  private  watercourse  between  its  heap!  and  the  field,  and  Ec 
is  the  efficiency  of  the  cultivator  who  waters  the  field. 

The  efficiency  of  any  distributary  is  the  fraction  whose  denom- 
inator is  the  quantity  entering  the  distributary  head,  and  the 
numerator  this  same  quantity  minus  the  loss  down  to  the  point  in 
question.  If  W  represents  the  waste  down  to  any  outlet,  Q  the 
discharge  at  the  head  of  the  distributary,  and  E°  the  efficiency  at 
the  point  under  consideration,  then 

-2TL—  7  .....  «> 

The  waste  W  down  to  any  point  may  approximately  be  ex- 
pressed as  the  product  of  the  loss  of  the  first  mile  into  some  func- 
tion of  the  length,  or 

W  =  APXLX-    .......     (5) 

or  substituting  in  the  above  equation,  we  get 

APXL* 
E  =i-      —  --  ,      .....      (6) 

where  AP  is  the  ascertained  loss  by  absorption  and  percolation 
in  the  first  mile  and  Lx  is  some  function  of  the  length,  which  will 
be  found  by  experiment  to  be  about  f  or  f  of  L  in  most  cases,  or 
near  the  head  of  the  distributary  Z,1. 

Taking  /  as  the  length  of  the  private  watercourse,  q  as  its 
discharge,  and  I*  as  the  same  function  of  its  length  as  in  the  case 
of  Lx,  we  have  the  efficiency  of  the  private  channel 

*-ii^22i.  (7) 


EFFICIENCY   OF   A   CANAL  301 

The  efficiency  of  the  cultivator  E  varies  between  .5  and  .9 
where  unity  represents  his  efficiency  at  the  theoretical  limit. 
Now  for  an  outlet  at  the  head  of  the  distributary  and  with  the 
irrigating  field  close  to  this  outlet,  L  =  o  and  /  =  o.  Therefore 
the  second  terms  of  the  equations  (6)  and  (7)  vanish  and  E° 
and  E°  each  =  i  ,  and  for  L  or  /  very  great,  E°  or  E*  =  o. 

An  application  of  these  rules  as  laid  down  by  Mr.  Beres- 
ford  is  given  in  the  following  cases:  Say  the  discharge  Q=  50  cubic 
feet  ;  that  the  outlet  is  at  the  tenth  mile,  whence  L  =  10;  the  losses 
from  percolation,  etc.,  being  1.25  in  the  first  mile  and  x  =  ,f.  The 
discharge  of  the  watercourse  q=i  cubic  foot,  1  =  6  furlongs,  and 
ap  =  .03  of  a  cubic  foot  per  furlong.  Then 

I.2S  X   10* 

.829; 


50 
X 


.820. 


i 
Say  £*-.75 

and  £=  .829  X  .82  X  .75=  .51; 

or  leaving  out  the  cultivator,  this  is  equal  to  .68.  That  is,  of 
each  cubic  foot  entering  the  distributary  head  only  .68  of  a  cubic 
foot  is  available  at  the  tenth  mile  and  6  furlongs.  Whatever 
the  actual  amount  of  loss  in  either  distributary  or  private  channel, 
it  varies  directly  with  L  and  /;  it  also  varies  directly  with  AP  and 
ap,  and  great  waste  is  due  to  the  cultivator  if  he  is  careless.  It 
will  thus  be  seen  from  the  above  that  every  effort  should  be  made 
to  reduce  the  value  of  AP  and  to  induce  the  cultivator  to  use  the 
greatest  possible  care  in  handling  the  water. 

From  the  above  it  is  evident  that  the  widest  field  for  improve- 
ment is  in  the  private  watercourses.  These,  generally,  are  much 
longer  than  is  necessary  and  are  usually  so  constructed  as  to  avoid 
low  lands,  whereas  flumes  or  proper  alignment  would  remedy 
this.  They  often  run  long  distances  through  sandy  soil,  which 
absorbs  the  water  and  frequently  parallel  each  other,  thus  ad- 
ding to  the  absorption  losses  by  unnecessarily  increasing  the 
wetted  perimeter.  Where  sandy  soil  is  encountered  or  depres- 


302  DISTRIBUTARIES 

sions  are  to  be  crossed  the  channels  should  be  puddled  or  cement- 
lined,  or  flumes  introduced. 

251.  Dimensions  of  Laterals. — Experiments  made  in  India 
show  that  the  greater  the  amount  of  water  discharged  by  a  dis- 
tributary the  smaller  will  be  the  proportion  of  cost  of  maintenance. 
Thus  a  channel  12  feet  wide  discharges  more  than  double  the 
volume  discharged  by  two  channels  each  6  feet  wide,  while  the 
cost  of  patrolling  and  repairing  the  banks  would  be  half  that 
of  both  the  smaller  ones.     Experience  has  proved  that  irrigation 
can  be  most  profitably  carried  on  from  channels  18  feet  wide 
at  the  bottom  and  carrying  about  4  feet  in  depth  of  water.     Thus 
on  the  eastern  Jumna  canals  during  the  years   1858  to   1860, 
inclusive,  the  expenditure  of  water  on  all  the  distributaries  of 
12  feet  bed  width  and  upwards  was  0.123  °f  tne  revenue,  while 
on  all  those  below  12  feet  it  was  0.223  or  nearly  double  that  of 
the  first.     From  the  same  examinations  the  relative  value  per 
cubic  foot  per  annum  on  channels  of  respectively  12,  6,  and  3  feet 
in  bed  width  was  as  10:7:4.     The  increased  action  of  absorption 
in  small  channels  with  diminished  volumes  and  velocities  accounts 
for  the  difference.     The  depth  of  water  should  accordingly  seldom 
be  less  than  4  feet  and  the  surface  of  the  water  should  be  kept  at 
from  i  to  3  feet  above  that  of  the  surrounding  country;  not  only 
to  afford  gravity  irrigation,  but  because  the  loss  by  absorption  is 
thereby  diminished. 

The  principle  which  is  so  commonly  employed  in  the  West 
on  private  channels  of  diverting  the  water  by  raising  it  to  the 
surface  of  the  country  by  means  of  earth  check-dams,  or  by  in- 
troducing plank  stops,  is  to  be  condemned.  It  converts  freely 
flowing  streams  into  stagnant  pools,  encourages  the  growth  of 
weeds  and  the  deposit  of  silt,  and  produces  a  generally  unhealthy 
condition.  It  is  moreover  extremely  wasteful  of  water,  much  of 
which  is  dissipated  because  of  loss  of  head  and  because  of  absorp- 
tion and  evaporation.  Where  these  stop  planks  or  checks  are 
used  in  private  channels  with  a  view  to  diverting  the  water  to  the 
irrigable  fields,  little  damage  is  done,  since  the  planks  remain  in 
but  a  short  time. 

252.  Capacities    of    Laterals. — In    planning    a    distributary 


DISTRIBUTARY   CHANNELS    IN    EARTH  303 

system  care  should  be  taken  so  to  design  each  of  the  laterals  that 
its  carrying  capacity  shall  be  equal  to  the  duty  which  it  has  to 
perform.  This  duty  is  dependent  on  various  factors,  which  are 
fully  discussed  in  Chapter  V.  The  total  area  to  be  commanded 
by  each  branch  and  its  laterals  should  be  known,  the  duty  of 
water  for  the  particular  soil  and  crops  estimated,  and  then  careful 
allowance  made  for  the  area  of  waste  land  (Art.  66),  being  that 
which  will  remain  uncultivated  or  will  be  occupied  by  roads, 
buildings,  etc.  Consideration  having  been  given  to  all  these 
factors,  the  capacities  required  of  the  different  channels  can  then 
be  readily  determined  and  their  dimensions  fixed.  The  simple 
form  of  computation  which  this  investigation  takes  is 
A'  =  gross  area  commanded  by  the  distributary; 

a  =  area  of  waste  land  ; 

6  =  proportion  of  culturable  land  which  is  to  be  irrigated 

during  an  average  year. 
Then 

A=(A'-a)xb,      ......     (i) 

in  which  A  is  the  net  area  to  be  irrigated,  and  is  equivalent  to 
the  same  symbol  in  the  formula  in  Article  58,  so  that  the  dis- 
charge of  the  distributary,  Q1  becomes 


Where  rotation  periods  are  to  be  imposed  on  a  canal 
(Art.  67),  careful  attention  must  be  paid  to  these  and  to  their  effect 
on  the  necessary  discharging  capacities  of  the  laterals,  and  the 
latter  must  therefore  be  designed  in  accordance  with  the  effect 
which  these  rotation  periods  or  tatils  will  have  on  their  required 
maximum  discharges. 

253.  Distributary  Channels  in  Earth.  —  The  cross-section 
of  the  larger  laterals  should  be  relatively  the  same  as  for  main 
canals  (Arts.  151  to  152).  In  designing  the  canal  banks  their 
top  width  should  be  sufficient  to  admit  of  easy  inspection.  On 
moderate-sized  laterals  3  feet  may  be  taken  as  the  minimum 
width.  Should  the  cut  be  so  deep  that  a  berm  is  necessary,  it  is 
always  well  to  let  the  latter  slope  away  from  the  canal  and  be 


3°4 


DISTRIBUTARIES 


drained  off  through  the  bank.  The  top  of  the  bank  likewise 
should  not  be  level,  but  should  drain  away  from  the  canal.  For 
smaller  laterals  or  private  channels  a  trapezoidal  cross-section 
both  for  the  bank  and  the  canal  will  usually  be  sufficient,  and  as 
far  as  possible  the  larger  portion  of  this  cross-section  should  be  in 
embankment,  thus  keeping  the  water  above  the  level  of  the 


FIG.  116.— View  of  Lateral  Head,  Galloway  Canal,  Cal. 

surrounding  country.  In  small  channels  it  is  not  necessary  to  con- 
struct berms,  to  give  subgrades  or  other  complex  cross-sections. 
254.  Wooden  Lateral  Heads  and  Turnouts. — Heads  to  laterals 
on  Western  canals  are  arranged  much  as  are  the  heads  of  main 
canals  and  wasteways.  They  consist  essentially  of  two  parts,  a 
regulator  or  check  below  the  head  on  the  main  canal,  to  divert  the 
water  into  the  lateral,  and  a  regulating  gate  in  the  latter  to  admit 
the  proper  amount  of  water.  These  heads  usually  consist  of  a 


WOODEN    LATERAL    HEADS    AND    TURNOUTS 


305 


wooden  fluming,  which  is  practically  an  apron  to  the  bed  of  the 
lateral,  and  planking  to  protect  the  banks.  In  this  fluming  are 
inserted  the  gates,  which  consist  either  of  flashboards,  as  in  Kern 


Variable 


•    Ffwtpliink 
" 


DETAIL  OF  MEASURING  WEIR 
m En 


5ft 


"ilraxuring 
Weir 


PLAN 


i;  l«  i 


d 


: 
. 

: 

i  —  r;    . 

J 

T                r 

-]  1 

' 

2  'x  12  ' 

«'«12- 

II 

2.12 

/.      . 

Note:  All  opening* 

/ 
over  »' 

Stringers 

_. 

u    I 

: 

r  ~~t 

wide  to  have  two  gate* 
ELEVATION 

FIG.  117. — Wooden  Head  to  Lateral,  Sun  River  Canal,  Montana. 

County,  California,  or  of  simple  wooden  lifting  gates,  as  in  most 
other  portions  of  the  West. 

In  Fig.  116  is  shown  a  distributary  head  on  the  line  of  the 
Calloway  canal  in  California.  Immediately  below  the  regulator 
is  shown  a  minor  headgate  or  turnout  leading  to  a  private  channel, 


20 


\v-*\ 

\XS2 



J, 

^7 

^: 

z.^/s_ 

•  — 

"J^/ 

r::: 

.- 

.__J 

E 

--.-9,9- 

—4 

WOODEN    LATERAL    HEADS   AND    TURNOUTS 


307 


3o8 


DISTRIBUTARIES 


while  a  sort  of  well  is  formed  in  the  lateral  flume  just  below  this 
farm  headgate  to  retard  the  velocity  of  the  current. 

The  standard  type  of  wooden  turnout  adopted  on  the  smaller 


12'2- >K  4'0-  ^O^1-' 9'9"---     -*J  4403.0 


Bars  from  both  side  and 
wing  walla  continuous 

orners.Alternate 
bars  from  both  Bets  in 
face  of  fillet 


FIG.  119. — Reinforced  Concrete  Turnout  with  lo-Foot  Drop,  Garland  Canal, 

Wyoming. 

laterals  of  the  Reclamation  Service  is  illustrated  in  Fig.  117. 
This  consists  of  a  timber  flume  and  wing- walls,  with  cross  flume 
taken  from  its  center  in  which  the  lateral  turnout  heads.  Simple 


WOODEN    LATERAL    HEADS    AND    TURNOUTS 


309 


lifting  gates,  one  or  more  in  number,  serve  to  check  the  flow  in 
the  principal  lateral  and  turn  the  water  into  the  branch  which  is 


• 

( 

• 

\      Cant  Iron                       / 
1     /           / 

'./ 

....... 

.., 

f 

• 

f 
r 

1 
i 
i 

.X         5 

_ 
' 

• 

v« 

%( 

• 

ji 

*  I: 

1 

• 

j 

1  F— 
c 

u  

/ 

t—  - 

9 

4-        -nr-       —r-        —  ^ 

IX 


SECT,ON«-6  SECTION   L"d 

FIG.  120. — Cast -Iron  Gates  for  Laterals,  Interstate  Canal,  Nebraska-Wyoming. 

controlled  by  a  similar  gate.     In  the  latter  is  a  trapezoidal  weir 
for  measuring  the  amount  of  water  admitted  at  various  heads. 


310 


DISTRIBUTARIES 


For  each  Gate:  1  eye  bolt, 
10  "x  ^'with  3"int.  dia. 
ring  as  shown  ^^ 


The  bed  of  the  branch  lateral  is  taken  off  at  a  height  of  one  or 
two  feet  above  that  of  the  principal  lateral. 

255.  Masonry  Lateral  Heads. — In  Europe  and  India  masonry 
is  employed  almost  exclusively  in  the  construction  of  distributary 

heads.  These  are  generally  so 
built  that  the  water  passing  from 
them  can  be  measured  and  the 
volume  turned  into  the  private 
channels  be  thus  ascertained  at 
any  time.  In  PL  XX  is  shown 
the  type  of  distributary  head 
used  on  the  canals  of  the  Punjab. 
On  the  Mutha  canals  in  Bombay 
a  V-shaped  weir  is  placed  in  the 
head  of  each  private  channel  or 
lateral  for  the  purpose  of  water 
measurement,  while  a  water- 
cushion  is  built  in  the  lower 
portion  of  the  distributary  head 
in  order  to  diminish  the  shock 
of  the  falling  water.  The  rules 
for  the  dimensions  of  \vater- 
cushions  are  given  for  main 
canals  (Art.  177). 

On  the  laterals  of  the  Recla- 
mation Service  turnouts  of  rein- 
forced concrete  or  of  terra-cotta  pipe  are  extensively  used.  The 
standard  turnouts  on  the  Yellowstone  canal  (Fig.  118)  consist  of 
rectangular  reinforced  concrete  pipes,  in  pairs  for  the  larger 
laterals,  or  of  terra-cotta  for  pipes  less  than  24  inches  cross-section 
passed  through  the  canal  banks.  At  entrance  and  exit  are  wing- 
walls  of  reinforced  concrete  9  inches  thick  with  cut-off  wall  of  same 
dimensions  carried  down  4  feet  below  the  bed  of  the  pipe.  Re- 
taining walls  of  same  material  support  the  canal  banks.  The 
walls  of  the  pipes  are  of  9  to  7  inches  thickness  and  are  encircled 
by  an  1 8-inch  cut-off  collar  under  the  center  of  the  canal  bank. 
Falls  are  frequently  concentrated  at  the  lateral  turnouts  and 


9i  i  5«  St.B.           .PlO      7  holes  ^  dia.  prorld 
fc"  Washer      X     1    \*    for  MliUnS 
(                                    \    N  -        /      .'„,,• 

(Same  for  all  gates)    \ 

i  \ 

/      "*/1 

0 

^3"^ 

/ 

x  a^ts" 

~    St.B. 

— 

4 

£ 

.H 
* 

i 

^H 
*•* 

3 

FIG.  121. — Wooden  Gates  for  Laterals, 
Interstate  Canal,  Nebraska-Wyo- 
ming. 


MASONRY   LATERAL    HEADS  311 

the  standard  type  of  turnout  with  fall  adopted  on  the  Garland 
canal,  Wyo.,  of  the  Reclamation  Sen-ice  is  illustrated  in  Fig.  119. 
The  main  canal  and  lateral  are  paved  and  the  banks  protected 
with  wing-walls  of  reinforced  concrete.  Above  the  fall  crest  are 
stop  gates,  of  wood  or  iron  (Figs.  120  and  121).  The  lateral 
heads  just  above  these,  and  is  taken  off  from  the  upper  level  at 
the  end  of  a  forebay  about  25  feet  deep.  At  the  head  of  the 
lateral  are  control  gates  set  in  grooves  in  the  concrete.  All  the 
gates  slide  vertically  and  are  lifted  by  a  screw  which  extends  up 
through  the  female  screw  of  a  hand  wheel. 

256.  Works   of    Reference.     Diversion  and  Canal  Works. 

AMERICAN  SOCIETY  OF  IRRIGATION  ENGINEERS,  ANNUAL  OF  THE.     Denver,  Colo- 
rado, 1893. 
BARROIS,    J.     Irrigation   in   Egypt.     Paris,    1887.     Translated   by  Major  A.   S. 

Miller,  U.  S.  A.     War  Department,  Washington,  D.  C. 

BUCKLEY,   ROBERT   B.     Keeping  Irrigation   Canals  Clear  of  Silt.     Proceedings 
Inst.  C.  E.,  vol.  58,  Part  IV.     London,  1879. 

—  Movable  Dams  in  Indian  Weirs.     Proceedings  Inst.  C.  E.,  vol.  60,  Part 
II.     London,  1880. 

Irrigation  Works  in  India  and  Egypt.     E.   &  F.  N.  Spon,  London,  1893. 


CAUTLEY,  COL.  SIR  PROBY  T.     Ganges  Canal  Works.     3  vols.     London,  1860. 

CHITTENDEN,  LIEUT.  H.  M.  American  Types  of  Movable  Dams  and  their  De- 
velopment. Engineering  News,  vol.  33,  No.  6.  New  York,  1895. 

DERRY,  J.  D.  Victorian  Royal  Commission  on  Water  Supply.  Fourth  Progress 
Report.  Melbourne,  1885. 

ETCHEVERRY,  B.  A.,  and  MEAD,  ELWOOD.  Lining  of  Ditches,  etc.  Bui.  188. 
Agricultural  Experiment  Station,  Sacramento,  Cal.,  1907. 

FLYNN,  P.  J.  Irrigation  Canals  and  Other  Irrigation  Works.  San  Francisco, 
1892. 

FORTIER,  SAMUEL.  Conveyance  of  Water.  Water  Supply.  Paper  No.  43. 
U.  S.  Geological  Survey.  Washington,  D.  C.,  1902. 

HALL,  WM.  HAM.  Report  of  the  State  Engineer  to  the  Legislature  of  California, 
Part  IV.  Sacramento,  1881. 

-  Irrigation  in  Southern  California.     Report  of  the  State  Engineer  to  the 
Legislature  of  California.     Sacramento,  1888. 

-  The  Santa  Anna  Canal  of  the  Bear  Valley  Irrigation  Company.     Trans. 
Am.  Soc.  C.  E.,  vol.  33,  No.  2.     New  York,  1895. 

HERSCHEL,  CLEMENS.     The  Holyoke  Dam.     Trans.  Am.  Soc.  C.  E.,  vol.    15. 

New  York,  1886. 

LEVINGE,  H.  C.     Soane  Canal.     Professional  Papers  VII.     Roorkee,  India,  1870. 
MEDLEY,   LIEUT.-COL.    J.   G.     Manual  of  Irrigation  Works.     Thomason   Civil 

Engineering  College,  Roorkee,  India,  1873. 
MONCRIEFF,   COLIN  C.  SCOTT.     Irrigation  in  Southern  Europe.      E.    &  F.  N. 

Spon.     London,  1868. 
MULLIN,  LIEUT. -GEN.  J.     Irrigation  Manual.     E.  &  F.  N.  Spon,  New  York  and 

London,  1890. 


312  DISTRIBUTARIES 

MURRAY,  STUART.     The  Goulburn  Weir  and  its  Dependent  System  of  Works. 
Victoria,  Australia,  1893. 

NAVIGATION  DE  LA  SEINE.     Exposition  Universelle  Internationale.     Paris,  1889. 

NEWBROUGH,   W.     Engineering  Notes  on  Irrigation   Canals.     School  of  Mines 
Quarterly,  vol.  15,  No.  3.     New  York,  1894. 

RECLAMATION  SERVICE,     U.  S.  Annual  Reports.     Washington,  D.  C. 

RIGHT  or  WAY  FOR  CANALS,  ETC.     Regulations  for  General  Land  Office,  Wash- 
ington, D.  C.,  1894. 

RONNA,  A.     Les  Irrigations.     Firmin-Didot  et  Cie.     2  vols.     Paris,  1889. 

SCOTT,   JOHN  H.     Irrigation  and  Water  Supply.     Crosby,  Lockwood    &  Com- 
pany, London,  1883. 

STEWART,   HENRY.     Irrigation  for  the   Farm,   Garden,   and  Orchard.     Orange^ 
Judd  &  Company,  New  York,  1889. 

SURVEYING    INSTRUCTIONS,    MANUAL    or.     General    Land    Office,    Washington, 
D.  C.,  1894. 

VERNON-HARCOURT,  T.  F.     Fixed  and  Movable  Weirs.     Proceedings  Inst.  C.  E., 
vol.  60,  Part  II.     London,  1880. 

WEISBACH,  P.   J.,  and  Du  Bois,  A.  JAY.     Hydraulics  and  Hydraulic  Motors. 
John  Wiley  &  Sons,  New  York,  1889. 

WHITING,  J.  G.     The  Nira  Canal.     Proceedings  Inst.  C.  E.,  vol.  77,  p.  423. 

WILCOX,  W.     Egyptian  Irrigation.     E.  &  F.  N.  Spon,  London,  1889. 

WILSON,  H.  M.     Irrigation  in  India.     Twelfth  Annual  Report  U.  S.  Geological 
Survey,  Part  II.     Washington,  D.  C.,  1891. 

—  American  Irrigation  Engineering.     Thirteenth  Annual  Report  U.  S.  Geo- 
logical Survey,  Part  II.     Washington,  D.  C.,  1892. 


CHAPTER  XIV 

APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

257.  Relation  of  Water  to  Plant-growth. — The  prevailing 
idea  of  irrigation  has  been  the  moistening  of  the  soil  by  spreading 
water  on  its  surface  so  as  to  produce  by  artificial  means  an  effect 
similar  to  that  caused  by  rain.  This  definition  goes  but  a  part 
of  the  way.  It  fails  to  take  account  of  the  effect  of  water  on  the 
physical  properties  of  soil,  and  the  physical  and  chemical  pro- 
cesses which  accompany  plant-growth.  More  broadly,  then, 
irrigation  may  be  defined  as  the  application  of  water  to  soil  at 
such  times,  in  such  amounts,  and  so  accompanied  by  cultivation 
of  the  soil  as  to  produce  the  condition  best  suited  to  plant-growth. 

After  light  and  heat,  water  is  the  most  important  of  the 
various  factors  which  influence  plant-growth.  Next  to  it  in 
importance  may  be  placed  the  physical  condition  of  the  soil, 
and  lastly,  plant-food.  It  is  on  these  five  factors,  light,  heat, 
water,  soil-texture,  and  plant-food,  that  the  machinery  for  plant- 
growth  is  dependent,  and  in  about  the  order  stated.  When  these 
are  furnished  in  the  right  amounts  and  at  the  right  times,  the 
best  results  may  be  expected  in  plant-growth,  and  of  these  the 
latter  three  may  be  controlled  to  a  material  extent  by  the  irrigator. 
In  our  arid  regions  heat  and  light  are  usually  furnished  in  abund- 
ance during  the  irrigating  season,  and  fortunately  the  clouds 
rarely  furnish  water  at  such  times  as  it  is  not  desired.  There- 
fore, having  at  his  disposal  a  satisfactory  irrigation  system,  the 
quality  and  amount  of  the  crops  which  may  be  produced  depend 
chiefly  on  the  knowledge  of  the  farmer  as  to  the  proper  mode  of 
utilizing  the  water  and  soil. 

Plants  do  not  naturally  grow  well  in  arid  regions,  because 
the  amount  of  moisture  evaporated  from  the  surface  of  the  leaves 
and  stems  by  the  domesticated  grain  and  vegetable  plants  com- 
monly cultivated  is  much  greater  than  the  amount  which  their 

313 


314       APPLICATION    OF   WATER,    AND    PIPE   IRRIGATION 

roots  can  absorb,  and  as  a  result  the  plant  dries  up.  Nearly  all 
of  our  cultivated  plants  have  originated  in  humid  climates,  and 
as  all  plants  evaporate,  or,  as  it  is  technically  known,  "transpire," 
large  amounts  of  water  in  the  process  of  their  growth,  one  of  the 
first  considerations  in  adapting  our  plants  to  Western  needs  is 
the  desirability  of  modifying  and  developing  them  so  as  to  encour- 
age the  growth  of  those  varieties  best  suited  to  the  conditions. 
The  physiological  effect  of  irrigation  is  to  furnish  for  absorption 
by  the  roots  of  plants  sufficient  moisture  to  balance  the  amount 
transpired  by  the  leaves.  In  the  humid  region  both  air  and  soil 
are  moist ;  in  the  arid  region  both  are  warm  and  dry.  The  effect 
of  this  dryness  of  the  air  is  to  increase  the  transpiration,  and  by 
keeping  up  a  greater  tension  in  the  plant  to  force  or  hasten  its 
growth.  It  is  for  this  reason  that  plants  cultivated  in  the  arid 
region  by  the  aid  of  irrigation  produce  larger  and  more  rapid 
growth  than  those  of  the  humid  regions — much  as  is  the  case  with 
hothouse  plants.  In  order  best  to  satisfy  the  conditions  of  plant- 
growth,  the  supply  of  moisture  should  never  fail  from  the  time 
the  seed  is  placed  in  the  soil  until  the  crop  is  fully  matured ;  and 
there  are  certain  times  when  the  cessation  of  the  supply  will  do 
more  harm  than  at  others — for  instance,  in  the  case  of  corn, 
when  grain  is  forming  in  the  ear.  Irrigation  does  away  with 
the  element  of  chance  by  supplementing  moisture,  by  making 
the  crop  larger  and  more  certain,  and  by  reducing  the  number 
of  acres  which  the  farmer  may  cultivate. 

For  easier  understanding  of  the  subject  of  plant-growth,  it 
may  be  stated  that  moisture  absorbed  by  the  suckers  or  hairs  of 
the  rootlets  rises  to  the  green  parts,  especially  the  leaves,  where 
it  assimilates  carbon  from  the  air  and  becomes  concentrated 
by  its  evaporation  or  transpiration.  What  remains  descends 
and  is  distributed  through  the  plant,  where  the  carbon  increases 
the  growth  of  its  various  organs  by  adding  to  the  cellular  struc- 
ture of  the  plant. 

Transpiration  takes  place  chiefly  during  the  heat  of  the  day, 
and  is  greater  when  the  air  is  dryer  and  the  soil  more  moist. 
The  amount  of  this  transpiration  is  enormous  at  times.  An 
ordinary  crop  of  meadow  grass,  cutting  two  tons  to  an  acre,  will 


RELATION   OF    SOIL   TEXTURE   TO   PLANT-GROWTH      315 

transpire  6J  tons  of  water  on  a  dry  day  and  about  527  tons  of 
water  during  a  growing  season;  an  average  crop  of  wheat  will 
evaporate  260  tons  of  water  per  acre  in  a  growing  season.  There- 
fore hay  evaporates  an  amount  of  water  equal  to  5^  inches  in 
depth  of  the  water,  and  wheat  an  amount  equal  to  about  2f 
inches  in  depth  of  water  in  an  irrigating  season.  The  soil  must 
therefore  be  maintained  in  a  condition  to  supply  this  incessant 
consumption  of  moisture,  and  as  soon  as  the  moisture  becomes 
deficient,  the  current  or  flow  of  sap  becomes  slackened  and  the 
plant  remains  stationary  or  dies.  One  hundred  pounds  of 
meadow  grass  contains  on  an  average  70  pounds  of  water,  and 
100  pounds  of  red  clover  over  80  pounds  of  water,  to  every  100 
pounds  of  fresh  material.  Such  moist  plants  as  lettuce,  cucum- 
ber, cabbage,  etc.,  contain  as  much  as  95  to  98  pounds  of  water 
to  even'  100  pounds  of  fresh  material.  These  facts  indicate 
the  importance  of  water  in  plant-growth  and  the  amount  which 
must  be  supplied  them,  especially  when  it  is  recalled  that  much 
of  the  moisture  reaching  the  soil  evaporates  from  its  surface  or 
percolates  through  it.  Experiments  by  Prof.  F.  H.  King  show 
that  in  Wisconsin  from  250  to  450  pounds  of  water  are  required 
to  produce  a  pound  of  dry  matter.  The  depth  of  water  required 
to  produce  a  pound  of  dry  matter  in  various  crops  ranged  from 
1 6  to  23  inches. 

All  plants  obtain  their  water  solely  through  their  roots,  there- 
fore a  well-developed  root  system  is  of  the  highest  importance 
to  their  welfare.  Consequently  any  process  which  will  aid  this 
development,  such  as  the  mode  of  application  of  water  or  attract- 
ing the  roots  in  various  directions  by  fertilization  or  tillage,  should 
be  carefully  considered.  Saturated  soil  is  detrimental  to  their 
growth,  while  half -saturated  soil  is  most  favorable  to  their  growth, 
and  therefore  to  that  of  the  plant. 

258.  Relation  of  Soil  Texture  to  Plant-growth. — Among 
the  more  important  methods  employed  for  conserving  the  mois- 
ture which  reaches  the  soil  from  natural  or  artificial  sources, 
and  of  making  it  available  to  the  plant  through  its  roots,  are,  i, 
cultivation  and  fertilization  of  the  soil  so  as  to  enable  it  to  absorb 
the  moisture  which  reaches  it;  2,  decreasing  evaporation  from 


31 6      APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

the  soil  surface,  through  producing  a  proper  tilth  or  mulching ; 
and  3,  decreasing  the  evaporation  from  the  plants,  Evaporation 
is  essential  to  pi  ant -growth,  yet  excessive  evaporation  is  wasteful 
of  moisture.  Under  certain  conditions  where  it  is  desirable 
to  reduce  evaporation,  which  is  less  rapid  in  moist  air  than  in 
dry  air  and  in  a  calm  than  in  strong  winds,  we  may  increase 
the  amount  of  moisture  in  the  air  and  thus  diminish  the  evapo- 
ration from  the  plant  by  sheltering  them  by  growths  of  trees 
suitably  disposed,  especially  in  regions  in  which  hot,  dry  winds 
are  prevalent. 

It  is  wasteful  to  allow  water  to  flow  off  soils  on  which  large 
sums  have  been  expended  in  the  introduction  of  irrigating  systems. 
Every  drop  of  water  which  flows  from  the  soil  is  an  indication 
that  the  latter  is  not  in  a  proper  physical  condition.  Either  the 
surface  slope  should  be  changed  by  grading  and  terracing,  or 
the  soil  be  made  more  open  and  porous  by  proper  preparation 
and  cultivation.  Also,  wherever  this  cultivation  has  been  prop- 
erly performed  water  is  more  rapidly  carried  into  the  soil,  and 
this  not  only  diminishes  the  loss  by  flow-off,  but  also  by  evapora- 
tion from  the  surface.  Where  moderate  deep  ploughing  will 
not  accomplish  the  object  desired,  subsoiling  must  be  resorted 
to.  There  is  much  wisdom  in  the  practice  in  vogue  among  many 
of  the  older  and  more  wasteful  irrigators  who  flood  their  land 
in  the  fall  after  their  crops  have  been  harvested.  The  common 
assumption  is  that  this  adds  so  much  moisture  to  the  soil  that 
it  is  retained  until  the  following  spring,  when  the  plants  require 
it.  The  real  explanation  of  the  benefits  of  fall  irrigation  is  that 
the  soil  which  is  helped  by  this  process  is  not  in  the  proper  physi- 
cal condition.  Nothing  rectifies  an  unfit  physical  condition  better 
than  water.  Therefore  subsoiling  or  deep  ploughing,  whereby 
the  soil  is  stirred  up  for  a  depth  of  12  to  1 8  inches,  breaks  up  its 
texture,  and  if  water  is  properly  applied  thereafter  beneficial 
effects  will  surely  be  felt  by  the  succeeding  crop.  Such  subsoil- 
ing should  rarely  be  performed  in  the  spring,  and  just  before 
planting,  as  it  works  an  injury  to  the  first  crop,  though  a  benefit 
to  the  succeeding  crops.  It  should  therefore  be  done  at  a  con- 
siderable time  before  the  crop  is  put  into  the  ground.  After  the 


RELATION    OF   SOIL   TEXTURE   TO    PLANT-GROWTH      317 

ground  has  once  been  deeply  subsoiled  it  should  be  frequently 
stirred  up  so  as  to  maintain  a  mulch  of  loose,  dry  soil  on  the  sur- 
face, and  thus  check  evaporation  and  aid  in  the  absorption  of 
moisture.  This  after-cultivation  should  rarely  be  to  a  depth 
exceeding  3  to  5  inches. 

There  are  many  curious  facts  connected  with  the  effect  of 
water,  cultivation,  and  fertilization  on  plant-growth.  It  is  well 
known,  however,  that  climatic  conditions,  changing  seasons, 
which  chiefly  include  light,  heat,  and  moisture,  have  more  effect 
upon  the  production  of  crops  than  is  obtained  through  any  degree 
or  kind  of  fertilization.  It  is  not  rare  to  have  a  crop  over  a  wide 
area  fall  off  one-third  or  even  one-half  by  reason  of  unfavorable 
climatic  conditions,  even  though  fertilizers  may  be  applied  most 
liberally.  Again,  soil  may  be  analyzed  and  be  found  wanting  in 
certain  chemical  requisites  for  plant-growth.  These  chemicals 
may  be  supplied  by  fertilizers  and  yet  produce  little  beneficial 
effect  on  plants,  while  some  other  fertilizer  or  some  other  methods 
of  cultivation  may  increase  the  crop  a  hundredfold,  in  some  way 
which  is  unexplained  by  chemical  analysis.  This  is  undoubtedly 
due  to  the  physical  effects  of  water  brought  more  intimately  in 
contact  with  the  soil  in  changing  its  texture,  or  to  physical  effects 
of  fertilizers  on  soil  rather  than  on  its  chemical  constituents. 
This  is  probably  by  changing  the  relation  of  soil  to  moisture 
and  heat  so  as  to  better  adapt  it  to  the  needs  of  the  particular 
plant.  Thus,  a  worn-out  soil  is  not  necessarily  deficient  in 
plant-food,  and  soils  which  are  barren  in  that  they  will  produce 
little  plant -growth  have  been  shown  by  chemical  analysis  to 
contain  an  abundant  supply  of  food  material. 

The  texture  of  soil  is  largely  determined  by  the  amount  of 
clay  and  the  manner  in  which  the  clay  particles  are  arranged  in 
the  soil.  Early  vegetable  and  fruit  soils  have  from  4%  to  10% 
clay,  but  are  too  light  for  wheat.  The  best  tobacco  lands  have 
from  15  %  to  20%  clay,  while  the  subsoil  in  good  wheat  and  grass 
land  has  from  20%  to  50%  clay.  Fertilizers  and  water  and  the 
temperature  at  which  the  latter  is  applied  have  great  effect  on 
the  texture  of  clayey  soils  by  changing  the  arrangement  of  the 
soil  grains.  Thus  the  subsoil  of  a  good  grass  land  from  decom- 


318      APPLICATION    OF   WATER,    AND    PIPE    IRRIGATION 

posed  limestone  has  40  %  to  50  %  clay,  yet  impervious  pipe-clays 
on  which  nothing  can  grow  owing  to  their  physical  texture  have 
been  analyzed  and  found  to  have  the  same  percentage  of  clay. 
This  is  because  the  grains  are  evenly  arranged  and  the  spaces 
between  them  through  which  water  moves  have  so  uniform  a 
size  that  water  can  scarcely  circulate.  On  the  other  hand,  in 
the  limestone  soil  having  the  same  proportion  of  clay  the  grains 
are  differently  arranged  or  are  granulated  and  held  close  against 
the  grains  of  sand,  thus  leaving  large  spaces  in  the  soil  through 
which  water  and  air  can  move  readily.  Experiments  have  been 
made  which  show  that  a  few  drops  of  ammonia  will  make  a  very 
coarse,  sandy  soil  almose  impervious  to  water,  as  will  also  car- 
bonate of  soda  or  black  alkali  (Art.  44).  Lime  and  organic 
matter  may  do  the  same,  yet  the  effect  of  lime  is  commonly  to 
render  heavy  soils  looser  and  more  friable. 

One  of  the  most  potent  influences  on  the  physical  texture 
of  soil  and  its  relations  to  plant-growth  is  the  amount  of  air-space 
in  the  soil  and  the  relation  of  this  to  the  amount  of  moisture 
contained  therein.  When  water  in  soil  amounts  to  over  80  %  of 
its  water-holding  capacity  it  is  detrimental  to  plant-growth.  This 
is  because  its  roots  are  immersed  in  water  and  the  soil  is  poor  in 
oxygen  or  air.  On  the  other  hand,  when  only  a  part  of  the  space 
in  the  soil  is  filled  with  water  and  the  air-supply  is  sufficient  ordi- 
nary plants  do  best;  that  is,  when  the  water  in  the  soil  amounts 
to  from  40%  to  60%  of  its  water-holding  capacity,  or  in  other 
words,  when  the  spaces  in  the  soil  contain  half  air  and  half  water. 
The  water-holding  capacity  of  a  soil  depends  on  the  amount  of 
space  between  the  soil  grains,  and  averages  40%  to  60%  of  the 
total  soil  volume,  therefore  the  amount  of  water  in  soil  should 
average  about  25  %  of  the  total  soil  volume,  and  there  should  be 
about  the  same  percentage  of  air-space,  dependent  upon  the 
character  of  the  soil  and  the  crop  to  be  grown.  Thus  the  amount 
of  water  in  soil  most  favorable  to  wheat  growth  is  12  to  20  pounds 
in  every  100  pounds  of  weight.  At  the  other  extreme,  the  water- 
holding  capacity  of  heavy  clay  soils  is  about  44  pounds  per  100 
pounds  of  saturated  soil.  The  plant  may  wilt  in  a  soil  contain- 
ing 10  %  to  12  %  of  moisture,  because  this  amount  may  be  so  small 


THEORY   OF   CULTIVATION    BY   IRRIGATION  319 

as  to  make  water  movement  to  the  roots  too  slow.  In  a  soil  of 
different  texture,  the  same  plant  may  not  suffer  when  the  amount 
of  moisture  in  the  soil  is  as  low  as  even  6%. 

259.  Theory  of  Cultivation  by  Irrigation. — From  what  has 
preceded  it  is  evident  that  the  correct  mode  of  applying  water 
to  soil  in  irrigating  various  crops  is  yet  but  a  matter  of 
merest  experiment.  It  is*  dependent  on  many  varying  fac- 
tors, among  which  are  the  physical  and  chemical  properties 
of  the  soil;  the  temperature  of  both  air  and  water;  and  the 
condition  of  the  crop  growth,  that  is,  the  time  when  it  requires 
irrigation. 

As  has  been  shown,  the  irrigator  must  strive  to  accomplish 
three  results  in  the  most  perfect  manner:  i,  he  should  not  apply 
cither  too  much  or  too  little  water,  but  just  sufficient  to  fill  about 
half  the  soil  spaces;  2,  this  water  should  be  applied  in  such 
manner  as  to  be  most  evenly  distributed  throughout  the  soil  in 
order  to  encourage  root-growth  in  all  directions;  3,  the  soil  should 
be  so  cultivated  as  to  create  the  loosest  texture,  and  thus  enable 
it  to  hold  the  largest  proportion  both  of  air  and  water  without 
settling  and  becoming  heavy  or  soggy.  The  physical  texture 
of  the  soil  is  beneficially  affected  by  deep  subsoiling  or  plough- 
ing, followed  by  rain  or  irrigation,  at  a  considerable  period  of 
time  before  the  planting  of  crops — preferably  in  late  fall,  when 
water  is  abundant.  After  seeding  the  soil  should  not  again  be 
deeply  ploughed,  and  should  be  frequently  stirred  for  a  few  inches 
in  depth  to  produce  a  surface  mulch,  especially  prior  to  irrigation, 
that  the  water  may  be  absorbed  and  not  evaporate  too  freely. 
The  first  cultivation  after  seeding  cannot  take  place  until  after 
the  plant  has  attained  sufficient  growth  to  render  it  possible  to 
avoid  injuring  it.  Certain  crops,  as  meadow-grass  and  hay, 
cannot  be  so  cultivated  without  injury  to  them.  Others  which 
are  planted  in  rows,  as  potatoes  and  corn,  and  orchards  and 
vineyards,  offer  excellent  opportunities  for  such  after  cultivation. 
A  well-cared-for  orchard  or  vineyard  should  never  show  a  sign 
of  weed  or  other  plant-growth  at  any  period  in  the  year.  Water 
cannot  be  applied  after  seeding  to  hay,  grain,  and  similar  crops, 
until  they  have  attained  such  a  height  above  the  ground  that 


320       APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

the  cracking  of  the  drying  soil  at  the  surface  will  not  seriously 
injure  the  crown  growth  and  delicate  stalks. 

This  brings  us  to  the  theory  of  time  of  application  and  amount 
of  water,  which  again  can  only  be  determined  by  experiment 
and  yet  is  dependent  upon  certain  general  principles.  Experi- 
ments made  at  the  Agricultural  Experiment  Station  of  Utah 
with  early  and  late  watering  of  hay  and  grain  crops  indicate 
for  the  latter  that  early  and  late  watering  produces  decidedly 
larger  crops  of  grain  and  but  little  less  of  straw.  In  the  climate  of 
Utah  early  irrigation  means  watering  in  the  middle  of  May  instead 
of  toward  the  middle  of  June,  as  is  customary,  and  late  irrigation 
means  watering  but  a  week  before  harvest  time.  The  effect  of 
usual  irrigation  instead  of  beginning  early  in  the  season  and 
ending  late  in  the  season  seems  to  be  that  the  early  irrigation 
affects  soil  temperature  as  well  as  its  physical  properties.  Grain 
plants  absorb  a  large  amount  of  moisture  during  the  time  when 
they  are  taking  on  stem  and  leaf.  There  is  but  little  moisture 
relatively  in  the  grain,  and  this  is  formed  rapidly  and  during  a 
short  period  of  time.  The  application  of  water  shortly  before 
harvesting  forces  the  grain,  makes  it  ripen  rapidly,  and  produces 
a  greater  ratio  of  grain  to  straw,  and  a  larger  yield  of  the  former 
as  well  as  of  the  whole  plant.  On  the  other  hand,  the  influence 
of  early  and  late  watering  on  potatoes  has  the  opposite  effect. 
In  the  experiments  referred  to  this  crop  suffered  materially  from 
the  effects  of  early  watering,  due,  it  is  believed,  to  watering  before 
the  plant  demanded  it,  thus  reducing  the  temperature  of  the  soil 
and  of  the  air  around  it  in  such  a  manner  as  practically  to  delay 
the  season.  In  comparisons  of  night  and  day  irrigation  it  tran- 
spired that  the  temperature  of  soil  irrigated  at  night  was  higher 
than  that  irrigated  in  the  day.  It  is  well  known  that  irrigation 
lowers  the  temperature  of  the  soil  and  therefore  retards  plant- 
growth  for  the  time  being,  so  that  there  appears  to  be  an  advan- 
tage in  this  point  for  night  irrigation;  yet  for  grain  crops  the  yield 
of  the  grain  is  greater  for  day  than  for  night  irrigation,  due, 
probably,  to  checking  of  growth  of  foliage.  On  the  other  hand, 
the  yield  of  straw  is  greater  as  a  result  of  night  irrigation. 

The  method  of   applying  water  is   also   indicated  to  some 


METHODS    OF    APPLYING    WATER  32! 

extent  by  the  foregoing  considerations.  Where  water  is  applied 
to  plants  -by  flooding,  especially  where  evaporation  is  great  and 
the  amount  applied  relatively  small,  it  results  in  a  shallow  growth 
by  attracting  the  roots  near  the  surface.  If  water  is  applied 
from  small  orifices  of  subsurface  pipes  it  encourages  the  root- 
growth  in  that  direction  only,  and  prevents  their  spreading  in 
other  directions.  Irrigation  by  deep  furrows  at  some  distance 
apart  one  from  the  other  tends  to  draw  root-growth  toward  the 
furrows,  though  in  certain  plants,  as  potatoes,  corn,  celery,  and 
others  which  are  naturally  grown  in  ridged  rows,  this  form  of 
irrigation  is  best  suited  to  root  development.  For  many  other 
varieties  of  plants,  and  especially  for  fruit-trees  and  vines,  the 
method  of  application  which  is  probably  best  suited  to  root  devel- 
opment is  by  means  of  many  small  but  deep  furrows  carrying 
small  volumes  of  water  which  shall  completely  enter  and  uni- 
formly saturate  the  soil  in  all  directions. 

As  to  time  and  amount  of  water,  each  soil,  crop,  and  climate 
is  a  law  unto  itself,  and  experience,  tempered  by  a  knowledge  of 
the  physical  and  chemical  effects  of  moisture  and  the  texture 
of  soil  on  plant-growth,  must  indicate  to  the  irrigator  the  course 
best  suitable  for  his  particular  conditions.  In  Chapter  V  this  sub- 
ject has  been  treated  in  a  general  manner,  and  additional  facts 
are  pointed  out  in  the  following  articles.  Each  condition  calls 
for  a  particular  depth  of  watering  and  a  particular  time  for 
applying  water  which,  if  properly  fulfilled,  will  produce  superior 
results. 

260.  Methods  of  Applying  Water. — The  cultivator  applies 
water  to  crops  by  various  methods,  depending  chiefly  on  the 
nature  of  the  crop  and  the  slope  of  the  surface  of  the  ground. 
These  are: 

1.  By  absorption  from  water  sprinkled  over  the  surface. 

2.  By  filtration  of  a  sheet  of  water  downward  through  the 
surface  of  the  soil. 

3.  By  lateral  percolation  from  an  adjacent  source  of  supply. 

4.  By  absorption  from  a  subsurface  supply. 

The  first  method  includes  irrigation  by  nature  in  the  form  of 
rain,  or  by  sprinkling  with  a  watering-pot  or  hose.  This  method 

21 


322       APPLICATION   OF   WATER,    AND   PIPE    IRRIGATION 

is  of  such  simple  character  as  to  require  no  further  consideration 
here. 

The  second  method  of  irrigation  is  called  flooding,  and  is 
accomplished  in  three  ways,  depending  on  the  character  of  the 
crop  and  on  the  slope  of  the  soil : 

1.  Flooding  of  meadows  by  simply  conducting  a  ditch  along 
the  upper  slope  of  the  land  and  allowing  the  water  to  flow  from 
this  completely  over  the  meadow. 

2.  Flooding  by  checks,  by  dividing  gently  sloping  surfaces 
into  level  benches  by  means  of  check  levees  and  permitting  the 
water  to  stand  in  these  as  in  still  ponds. 

3.  Flooding  by  the  checkerboard  system,  by  dividing  nearly 
level  ground  into  rectangles  by  surrounding  levees  and  allowing 
the  water  to  stand  in  these. 

The  third  method  of  application  is  generally  called  the  furrow 
method  and  is  accomplished  in  four  ways: 

1.  By  running  small  ditches  close  to  fruit-trees  and  vines, 
and  allowing  the  percolation  from  these  to  moisten  their  roots. 

2.  By  letting  a  large  number  of  small  streams  flow  from 
flumes  through  ditches  between  fruit-trees  and  vines,  and  allow- 
ing the  water  to  percolate  from  these  to  their  roots. 

3.  By  flowing  the  water  in  small  streams  through  the  furrows 
between  such  crops  as  potatoes  and  corn,  and  thus  gradually 
moistening  them. 

4.  By  drilling  grain  in  rows  or  shallow  furrows  and  running 
the  water  through  these.     This  is  practically  a  combination  of 
flooding  and  sidewise  soakage. 

The  fourth  method  of  irrigation  is  conducted  by  laying  pipes 
underground  and  having  outlets  in  these  under  each  fruit-tree; 
or  by  so  placing  these  outlets  that  the  water  escaping  therefrom 
shall  moisten  the  roots  of  vines  and  trees  near  by. 

261.  Preparation  of  Ground  for  Irrigation. — The  amount 
and  kind  of  preparation  required  to  put  ground  in  the  most 
suitable  condition  for  irrigation  is  indicated  in  the  above  general 
discussion.  In  every  case  where  the  best  results  are  desired 
the  greatest  care  should  be  taken  in  properly  grading  and  laying 
out  the  irrigable  lands.  A  little  time  and  money  devoted  in 


PREPARATION   OF   GROUND    FOR    IRRIGATION  323 

the  beginning  to  a  proper  preparation  of  the  land  will  be  more 
than  repaid  in  the  saving  of  water  and  the  ease  and  cheapness 
with  which  it  can  be  applied.  Land  once  properly  prepared 
can  always  be  cheaply  and  easily  maintained  in  the  best  condi- 
tion. The  real  secret  of  successful  irrigation  is  intensive  culti- 
vation, by  which  is  meant  careful  and  tireless  attention  to  a 
very  small  area  of  land  by  one  individual.  A  single  farmer 
can  produce  larger  and  better  crops  and  obtain  greater  profit 
from  thorough  and  careful  cultivation  of  10  to  20  acres  than 
from  superficial  cultivation  of  100  acres.  Where  land  is  properly 
prepared  one  man  can  quickly  and  thoroughly  handle  water 
on  ten  acres,  whereas  two  or  three  men  would  not  produce  as 
satisfactory  results  on  the  same  area  illy  graded  and  prepared. 

Where  water  is  to  be  applied  by  the  flooding  method  great 
care  should  be  taken  to  produce  a  perfectly  uniform  slope  and 
surface.  This  should  be  done  by  the  use  of  some  of  the  grading 
tools  which  are  now  on  the  market,  in  connection  with  levels 
taken  to  determine  within  an  inch  or  two  as  maximum  limits 
the  slope  of  the  land.  If  the  surface  is  particularly  uniform, 
deep  ploughing  followed  by  harrowing  and  then  dragging  over 
the  surface  a  heavy  log  or  beam  or  some  other  device  for  leveling 
the  land  will  suffice.  At  other  times  the  slope  may  be  too  great 
to  permit  of  irrigation  by  flooding,  because  it  would  produce  such 
a  velocity  as  to  cause  erosion  of  the  soil.  This  is  to  be  corrected 
by  grading  the  soil  so  as  to  form  checks  or  in  extreme  cases  by 
terracing,  which  is  but  an  exaggerated  form  of  check.  If  the 
surface  is  uneven  the  water  will  stand  about  in  pools,  so  that 
certain  portions  of  the  land  will  receive  too  much  and  become 
supersaturated  while  other  places  will  be  high  and  dry.  It  is 
only,  therefore,  by  the  creation  of  a  uniform  surface  that  water 
can  be  satisfactorily  applied  by  the  flooding  method. 

Where  the  soil  is  to  be  prepared  for  irrigation  by  furrows, 
and  especially  where  these  furrows  are  to  be  small  and  narrow, 
as  in  the  drill  method  of  irrigation,  even  greater  care  must  be 
taken  than  in  the  flooding  method  in  producing  the  proper  slope 
and  surface  level.  If  the  slope  of  the  land  is  too  steep  the  furrows 
and  drills  will,  because  of  the  velocity  of  the  water,  be  rapidly 


324       APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

eroded.  If  the  slope  is  too  slight  the  water  may  take  so  long 
in  flowing  across  the  fields  as  to  be  all  evaporated  or  absorbed 
before  it  reaches  the  further  end.  Too  steep  slopes  may  be 
rectified  by  running  small  ditches  or  flumes  down  the  slope  of 
the  ground  and  inserting  falls  in  them  to  overcome  excess  of 
slope,  and  by  turning  the  water  from  these  into  lateral  furrows 
and  drills  which  run  at  such  an  angle  as  procures  the  proper  fall. 
262.  Sidehill  Flooding  of  Meadows. — This  method  is  the 


FIG.  122. — Diagram  Illustrating  Flooding  of  Meadows. 


most  wasteful  of  water,  but  it  is  that  most  commonly  practised 
in  the  cultivation  of  grass  and  cereals.  Wild  meadow-lands 
and  hayfields  are  flooded  by  simply  turning  the  water  on  them 
when  the  slope  of  the  ground  is  sufficient  and  allowing  it  to  sink 
into  the  soil.  To  accomplish  this  the  water  is  made  to  enter  the 
field  at  its  highest  point  in  a  ditch  conducted  around  an  upper 
contour  of  the  field.  Breaks  are  made  at  intervals  in  the  side 
of  the  ditch,  and  the  water,  being  allowed  to  flow  through  these, 
finds  its  way  in  a  thin  sheet  over  the  field  (Fig.  122).  This  method 


FLOODING    BY   CHECKS 


325 


is  very  expensive  of  water  and  can  be  employed  on  but  few  soils 
since  clayey  soils  bake  or  parch,  forming  a  thin  crust  which 
kills  the  growth  of  plants.  Instead  of  making  breaks  in  the 
side  of  the  ditches,  checks  are  sometimes  formed  by  little  dams 
of  earth  or  wood. 

263.  Flooding  by  Checks. — This  method  consists  in  run- 
ning check  levees  around  the  slope  of  the  land  on  contour  lines. 
These  are  low  ridges  of  earth  about  i  foot  in  height,  turned  up 
with  a  plough  or  scraper  and  placed  at  such  distances  apart 
that  the  crest  of  each  shall  be  on  a  level  with  the  base  of  the 
check  above  it  (Fig.  123).  If  properly  built  these  checks  will 


SCCnon      on    a-* 


FIG.  123. — Irrigation  by  System  of  Check  Levees. 

last  for  many  years,  and  the  field  may  be  ploughed  and  reploughed 
without  injury  to  them  or  their  in  any  way  affecting  the  handling 
of  the  crops.  In  comparatively  level  country  like  that  in  Kern 
county,  California,  the  distributary  ditches  are  placed  as  much 
LS  a  quarter  of  a  mile  apart,  their  banks  forming  two  of  the  bound- 
ing ridges  or  levees,  the  third  or  lower  boundary  being  a  contour 
levee  connecting  the  ditch  banks.  The  less  the  height  of  this 
levee  the  better,  because  the  quantity  of  water  spread  over  the 
land  will  be  of  more  uniform  depth  and  will  interfere  less  with 


326        APPLICATION    OF   WATER,    AND    PIPE    IRRIGATION 


PLAN 


ploughing  and  harvesting;  the  greater  the  width  of  the  levee 
base  the  better.  From  6  to  12  inches  is  the  best  height,  and 
from  15  to  20  feet  the  best  width  of  base.  In  such  country  as 
that  described  the  checks  range  from  10  to  50  acres  each  in  area 
and  require  from  12  to  20  miles  of  levee  per  square  mile  of  check, 
while  a  mile  of  levee  contains  about  3000  cubic  yards  of  earth. 

The  water  is  run  through  the 
ditches  (Fig.  123)  and  ad- 
mitted by  gates  into  each 
separate  check.  When  the 
latter  is  full  the  water  is  drawn 
off  to  the  next  lower  level,  or 
if  the  soil  is  porous  it  is  al- 
lowed to  stand  until  it  has 
been  absorbed. 

264.  Flooding  by  Check- 
erboard System  of  Squares.— 
This  method  is  practised  ex- 
tensively on  the  level  plains  of 
Southern  Arizona  and  in  In- 
dia. The  fields  are  divided 
into  squares  of  from  20  to  60 
feet  on  each  side  (Fig.  124), 
and  these  are  separated  by 
ridges  or  levees  of  from  10  to 
12  inches  in  height  in  which 
openings  are  made  leading 


FIG.  124. — Flooding  by  System  of  Squares. 


from  one  square  to  the  other. 


In  some  cases  the  fields  are 
divided  into  much  larger  squares,  often  of  an  acre  in  extent, 
depending  on  the  slope  of  the  ground.  Again,  especially  in 
India,  very  small  squares  are  employed,  and  the  height  of 
the  dividing  ridges  is  made  as  low  as  6  inches,  so  that  these  do 
not  interfere  materially  with  the  harvesting  and  ploughing  of 
the  fields.  The  chief  objection  to  this  method  is  the  obstruc- 
tion created  by  the  check  levees.  When  these  can  be  placed 
far  enough  apart  they  interfere  but  little  with  the  operations  of 


. 
FLOODING  BY  TERRACES  327 

the  cultivator:    otherwise  he  must  use  spade  and  hoe  instead 
of  plough. 

Water  is  admitted  to  one  square  at  a  time  and  is  either  per- 
mitted to  soak  into  the  soil  or  is  drawn  off  to  be  used  in  the  next 
square  below,  much  as  in  the  check  method.  The  chief  crops 
irrigated  by  this  method  are  hay,  grain,  and  vegetables.  Where 
flooding  is  practised  by  checks  or  squares,  anywhere  from  4  to 
12  inches  in  depth  of  water  is  let  on  at  a  single  watering.  The 
number  of  these  waterings  may  range  between  two  and  five  in 
a  season,  according  to  the  crop,  soil,  and  climate.  Rice  and 
sugar-cane  are  irrigated  in  India  and  South  America  by  squares. 
These  crops  require  a  very  large  amount  of  water,  and  as  a  con- 
sequence the  height  of  the  levees  is  rarely  less  than  a  foot  and 
is  often  greater.  These  are  filled  with  water  and  it  is  allowed 
to  stand  on  them  for  long  periods  of  time,  the  soil  being  seldom 
permitted  to  dry. 

265.  Flooding    by    Terraces. — This    method     is    employed 
chiefly  in  India  and  China,  and  has  recently  been  adopted  on  a 
small  scale  in  a  few  neighborhoods  in  California.     It  consists  of 
laying  out  steeply  sloping  sidehill  ground  in  terraces,  the  lower 
sides  of  which  are  surrounded  by  high  levees.     These  are  practi- 
cally exaggerated  forms  of  checks,  and  as  employed  in  California 
are  maintained   and  operated  on  the  same  general  principle, 
though  thoy  receive  a  large  proportion  of  their  water-supply 
from  the  drainage  of  the  hillsides  above.     As  employed  in  India 
or  China,  these  terraces  also  receive  their  water-supply  chiefly 
from  the  drainage  above,  and  hold  it  as  in  a  small  tank  or  reser- 
voir of  a  few  feet  in  depth.     As  the  water  soaks  into  the  soil  of 
the  terrace,  rice  or  similar  crops  are  sown,  and  the  amount  of 
moisture  retained  in  the  earth  by  such  a  volume  of  water  entering 
)t  is  sufficient,  with  the  addition  of  what  may  be  received  from 
occasional  rains,  to  irrigate  the  crops. 

266.  Furrow    Irrigation    of    Vegetables    and    Grain. — This 
method  is  practised  by  laying  the  field  off  in  shallow  ditches 
run   around   its  upper  slope.     From  these  ordinary  V-shaped 
plough  furrows  radiate  down  the  slope  of  the  field,  and  between 
these  vegetables,   potatoes,   or  grain  are  planted.     Where  the 


328      APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

country  slopes  more  irregularly  or  steeply  the  furrows  are  run  at 
various  angles  down  the  slope  in  such  manner  that  their  grade 
shall  not  be  too  steep.  The  water  is  then  turned  into  a  few  of 
these  furrows  at  a  time  by  blocking  the  ditch  above  with  a  clod 
of  dirt  or  a  board  (Art.  266),  and  the  water  penetrates  by  side- 
wise  soakage  to  the  crops.  Grain  is  irrigated  by  the  furrow 
method  by  ploughing  a  ditch  along  the  upper  slope  of  the  field 
as  above  described,  and  by  drilling  the  grain  down  the  slope  of 
the  field  radially  from  this  ditch  and  permitting  the  water  to 
enter  a  few  of  the  drill-rows  at  a  time.  Grain-fields  are  some- 


FIG.  125. — Furrow  Irrigation  of  Grain. 

times  prepared  for  this  method  of  combined  flooding  and  fur- 
row irrigation  by  rolling  the  field  after  the  grain  is  planted,  with 
a  heavy  roller  on  the  surface  of  which  are  annular  projections 
of  a  few  inches  in  height  and  from  \  to  i  foot  apart.  These 
make  grooves  in  the  surface  of  the  soil  in  a  direction  parallel 
to  the  slope,  and  the  water  is  admitted  to  these  and  permitted 
to  flow  through  them  as  in  the  case  of  ploughed  furrows  or  drill- 
rows. 

267.  Combined  Flooding  and  Furrow  Irrigation  of  Orchards. 

—Where  trees  are  directly  flooded  the  tendency  of  the  water  is 

to  bring  the  roots  to  the  surface  and  thus  enfeeble  them.     To 

prevent  this  furrows  are  run  from  the  upper  ditches,  generally 

in  a  double  row,  one  on  either  side  of  and  at  a  short  distance 


330        APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

from  the  trees  or  vines  (Fig.  125).  By  this  means  the  water  per- 
colates into  the  soil  and  reaches  the  roots  of  the  tree  by  sidewise 
soakage  at  some  depth  beneath  the  surface,  thus  moistening 
and  encouraging  their  growth.  Another  method  of  flooding 
orchards  is  to  protect  the  trees  by  earth  ridges  thrown  up  so  as 
to  prevent  the  water  from  reaching  within  3  to  4  feet  of  them. 
In  this  method  the  entire  field  is  flooded  with  the  exception  only 
of  the  areas  immediately  adjacent  to  the  trees.  This  practice 
is  wasteful  of  water,  as  much  more  is  employed  than  is  required. 
Olive-  and  orange-trees  are  watered  from  three  to  four  times  in 


FIG.  126. — Furrow  Irrigation  of  Orchard,  Riverside,  Cal. 

a  season ;  vines  once  or  twice,  and  often  not  at  all  after  the  first 
few  seasons. 

268.  Irrigating  Orchards  by  Small  Furrows. — This  method 
is  practised  chiefly  in  Southern  California.  The  principle  under- 
lying this  method  is  that  the  ground  shall  be  put  in  the  condition 
which  it  would  be  in  after  several  days  of  long  soaking  rain,  rather 
than  in  the  condition  which  it  would  be  in  after  a  small  cloud- 


IRRIGATING   ORCHARD    BY   SMALL   FURROWS  331 

burst,  which  is  the  condition  resulting  from  other  methods  of  sur- 
face irrigation.  This  is  done  not  by  running  large  streams  of 
water  through  the  furrows  for  a  short  period  of  time,  but  by  run- 
ning small  streams  through  them  for  a  long  time.  It  is  accom- 
plished (Fig.  126)  by  running  a  number  of  ploughed  furrows 
between  the  rows  of  trees,  the  nearest  furrow  being  as  close  as 
practicable  to  the  trees,  and  the  distance  between  furrows  from 
2  to  3  feet.  The  volume  of  each  of  the  streams  running  through 
these  does  not  exceed  one  four-hundredth  of  a  second-foot,  and 
the  water  is  run  through  them  for  two  and  three  days  at  a  time. 
Where  the  soil  is  not  too  loose  or  sandy  this  method  seems  to  give 
the  best  results  for  fruits  and  vines  and  may  be  used  with  some 
success  on  grain  and  corn. 

The  moistening  of  the  roots  by  sidewise  percolation  from 
shallow  furrows  between  tree  rows  is  not  nearly  so  complete  as 
generally  supposed.  This  is  admirably  indicated  by  a  series  of 
experiments  conducted  by  R.  H.  Loughridge  in  California  in 
1908.  As  shown  in  figure  127  the  movement  of  water  in  porous 
loam  soils  is  downward;  it  percolates  laterally  only  2  or  3  feet 
from  the  furrow  and  fails  entirely  to  reach  through  the  tree  rows 
or  under  the  trees  unless  the  furrows  are  very  close  to  them 
(Fig.  i2yA).  An  impervious  layer  like  hardpan  causes  sidewise 
movement  to  the  extent  of  4  to  5  feet,  greater  wetting  of  the 
surf  ace,  and  increased  loss  by  evaporation  (Fig.  1276).  In  grit 
the  movement  is  more  rapid  downward  (Fig.  1270). 

In  loose  soil  an  extreme  depth  of  26  feet  was  reached;  in 
compact,  impervious  soil  the  depth  was  but  12  inches  after  three 
days.  Shallow  furrows  do  not  give  as  good  results  as  deep  ones, 
as  they  allow  the  water  to  rise  on  either  side  by  capillarity  and 
evaporate,  while  deep  furrows  allow  the  retention  of  nearly  all 
the  water  applied. 

In  order  that  the  method  shall  be  successful,  the  laterals 
from  which  the  furrows  are  filled  and  which  come  from  the  main 
distributary  must  have  a  uniform  depth  and  slope  to  a  degree 
which  cannot  be  secured  in  open  earth.  This  is  accomplished 
by  running  wooden  laterals  or  flumes  along  the  surface  of  the 
ground  down  its  slope.  These  simple  flumes  are  but  a  few  inches 


332       APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

in  cross-sectional  area,  generally  the  width  of  a  plank  at  base 
and  on  the  sides.  They  are  given  a  sufficient  grade  to  produce 
a  good  velocity,  and  where  the  natural  slope  is  too  great  falls 


Ft,     0      1     2      3      4       5 


7      8      9     10    11     12    13     14    15     16     17    18    19    20    21 


10     11     12      13     14      15     16      17     18       19     20 


FIG.  127. — Extent  of  Percolation  from  Small  Furrows;  A,  in  Loose  Loam;  B,  in 
Hardpan;    C,  in  Impervious  Grit. 

are  introduced.  The  water  escapes  from  these  flumes  into 
the  furrows  through  auger-holes  bored  in  their  sides  opposite 
each  furrow  and  on  a  level  with  the  bottom  of  the  flume  (Fig.  126). 


DITCH   AND    FURROW    CHECKS 


333 


The  flow  through  these  holes  is  regulated  by  wooden  buttons  or 
plugs  which   are  inserted  in  them.     For  small  orchards  these 
flumes  generally  have  a  capacity  of  about  £  a  second-foot.     Fruit 
trees  thrive  well  on  from  three  to  five  waterings  and  vines  on  from 
two  to  three  waterings  when  supplied  by  this  method. 

269.  Ditch  and  Furrow  Checks. — Water  flowing  in  minor 
ditches  must  be  checked  and  turned  into  the  field  channels  and 
furrows  by  some  temporary  and  inexpensive  means.  Likewise 
water  flowing  through  the  smaller  furrows  must  be  turned  from 


FIG.  128. — Using  Canvas  Dam. 

these  into  other  furrows  and  drill-rows  by  some  similar  temporary 
expedient.  The  plan  of  erecting  wooden  structures  at  such 
points  is  not  only  expensive  but  inconvenient,  as  permanent 
structures  interfere  with  the  working  of  the  fields.  The  form 
of  check  which  works  about  as  satisfactorily  as  any  on  the  larger 
field  ditches  is  the  canvas  dam  (Fig.  128),  which  consists  of  a 
simple  piece  of  scantling  from  5  to  7  feet  long,  according  to  the 
width  of  the  ditch,  on  which  is  nailed  and  held  by  a  lath  a  piece 
of  10-  or  i2-ounce  canvas  from  50  to  60  inches  wide,  preferably 
large  enough  to  afford  ample  protection  to  the  sides  of  the  ditch, 


334      APPLICATION   OF   WATER,    AND   PIPE   IRRIGATION 

and  about  3  feet  in  length.  At  the  bottom  of  this  piece  of  canvas 
laths  and  a  rope  should  be  fastened  for  properly  manipulating  it. 
The  scantling  is  laid  across  the  ditch  banks,  and  the  canvas 
conforms  to  the  inner  surface  of  the  ditch,  and  is  held  in  place 
by  a  stake  of  wood  driven  through  the  rope  loop  at  the  bottom. 
This  canvas  dam  obviates  the  necessity  of  injuring  the  sides 
of  the  ditch  by  temporary  earth  or  wood  dams.  The  older  and 
more  common  mode  of  checking  water  in  ditches  or  furrows  is  by 
throwing  dirt  into  these  from  either  bank  until  the  flow  of  water 
is  blocked.  This  method  is  still  probably  the  most  satisfactory 
for  use  in  small  furrows  and  drills  which  a  spadeful  of  earth  or 
a  small  stone  will  block. 

Another  form  of  dam  than  that  of  canvas,  and  which  is  not 


FIG.  129. — Steel  Dams. 


unsatisfactory  under  certain  conditions,  is  that  of  a  thick  piece 
of  sheet  metal,  which  may  have  a  couple  of  handles  at  the  top, 
and  be  fastened  to  a  small  wooden  scantling.  This  piece  of 
sheet  iron,  which  should  be  curved  or  pointed  at  the  bottom, 
can  be  forced  vertically  into  the  ground  in  a  manner  similar  to 
that  of  driving  a  shovel  into  the  bed  of  the  ditch,  and  this  will 
procure  a  satisfactory  temporary  check  (Fig.  129). 

270.  Subsurface  Irrigation. — Irrigation  from  beneath  the 
surface,  or  subirrigation,  is  theoretically  one  of  the  most  eco- 
nomical and  satisfactory  methods  of  applying  water  to  plants. 
The  idea  is  to  replace  seepage  from  above  by  absorption  from 
below,  which,  to  be  perfect,  should  not  wet  the  surface.  As 


SUBSURFACE    IRRIGATION  335 

a  result  the  water  thus  applied  to  the  soil  should  theoretically 
have  the  same  temperature,  and  thus  not  set  the  plant-growth 
back,  and  as  long  as  the  water  does  not  reach  the  surface  it  is 
presumable  that  just  the  right  amount  has  been  applied  and 
not  sufficient  to  saturate  the  soil.  This  is  effected  by  laying 
pipes  underground,  and  these  derive  their  supply  from  distrib- 
utaries, which  are  usually  of  vitrified  pipe.  The  cost  of  pre- 
paring land  for  this  mode  of  irrigation  is  relatively  great,  but 
is  more  than  repaid  by  the  saving  in  water  charges,  since  the 
duty  of  water  reaches  as  high  as  500  to  1000  acres  per  second - 
foot.  This  method  has  been  most  extensively  employed  among 
the  valuable  fruit-lands  of  Southern  California,  which  are  usually 
divided  into  orchard  lots  of  from  10  to  20  acres  each.  The 
company  distributing  pipe  terminates  at  the  highest  point  in 
each  of  these  lots,  and  from  this  the  subirrigation  pipes  of  the 
farmer  are  conducted  through  the  orchards. 

In  practice  this  method  has  not  proven  as  satisfactory  as 
had  been  anticipated.  Roots  clog  the  orifices  of  the  subirriga- 
tion pipes,  and  uniform  watering  of  the  soil  such  as  is  required 
to  produce  the  best  form  of  root-growth  is  practically  impossible. 
This  is  true  even  when  roots  do  not  clog  the  orifices,  and,  more- 
over, growth  of  these  roots  has  also  the  effect  of  bursting  and 
destroying  the  pipes.  Yet  in  some  localities  where  this  method 
has  been  introduced  and  great  care  and  attention  have  been 
paid  to  the  maintenance  of  the  subirrigation  pipes  very  satis- 
factory results  are  still  achieved.  Subirrigation,  while  attractive 
theoretically,  is  considered  a  failure  even  in  Southern  California, 
where  it  has  been  most  thoroughly  tried  and  no  expense  spared 
to  make  it  effective.  This  method  does  not  work  well  in  sandy 
or  gravelly  soils,  because  of  the  tendency  of  the  water  to  drain 
off  through  these,  and  this  may  account  for  the  disfavor  into 
which  this  method  has  fallen  in  Southern  California,  where  this 
class  of  soils  predominates.  This  system  works  best  in  loamy 
and  silty  soils,  where  the  effects  of  capillarity  are  greatest,  and 
this  fact  may  account  for  the  favor  which  this  system  has  met 
with  in  portions  of  Kansas.  Experiments  on  subirrigation  at  the 
Utah  Agricultural  Station  developed  the  fact  that  for  the  climate 


APPLICATION    OK    WATKK,    AND    PIPM    IkKKiATION 

and  soil  subirrigation  failed  to  supply  sufficient  moisture  for 
growing  crops,  as  the  lateral  movement  of  water  due  to  capillarity 
was  too  slow  to  furnish  the  requisite  moisture  for  transpiration. 

271.  Subirrigation    Pipes. — These    are    made   of    sheet    iron 
or  steel  or  of  some  porous  or  glazed  material.     Glazed  earthen- 
ware   pipes   are  more  popular  than  any  other  form.     Asphalt- 
concrete  pipes  have  been  successfully  employed  for  subirrigation 
and  have  the   advantage  over  simple  concrete  pipes  of  being 
impervious  to  water.     These  are  united  by  heating  so  as  to  form 
a  continuous  pipe.     These  distributing  pipes  are  in  some  cases 
as  small  as  2  inches  in  diameter,  and  from  this  they  range  to  6 
inches  where  the  principal  distributaries  are  reached. 

Subirrigation  pipes  are  laid  in  open  trenches  at  a  depth  of 
i  to  i £  feet  below  the  surface,  parallel  to  the  rows  of  trees  or  vines 
in  the  orchard,  and  the  trench  is  then  filled  in  with  earth.  Irriga- 
tion is  effected  from  these  pipes  sometimes  by  cutting  a  hole  on 
the  upper  side  and  inserting  therein  a  wooden  plug  opposite  each 
tree  or  vine.  Each  plug  is  surrounded  by  a  larger  stand  pipe  set 
loosely  on  top  of  the  distributary  pipe,  open  at  the  bottom  and 
reaching  to  the  surface  of  the  ground  for  the  purpose  of  keeping 
the  dirt  away  from  the  outlet  and  rendering  it  accessible  at  all 
times  for  inspection.  The  process  of  irrigation  consists  in  simply 
turning  the  water  off  or  on  from  the  main  pipe,  when  it  finds  its 
way  through  the  outlets,  fills  the  standpipe,  and  slowly  percolates 
to  the  surface  of  the  ground.  One  of  the  most  satisfactory 
methods  of  letting  the  water  escape  consists  in  cutting  a  section 
several  inches  in  length  out  of  the  continuous  pipe  where  the  plug- 
hole should  be  inserted,  and  by  replacing  it  by  a  U-shaped  shoe 
placed  below  the  cut  in  the  pipe.  A  tile  a  little  longer  than  the 
gap  covers  it  and  water  escapes  between  the  two  surfaces. 

272.  Main  and  Distributing  Pipes. — It   is  frequently  found 
desirable  to  use  pipes  on  main  canal  lines  as  inverted  siphons, 
or  pressure  pipes  to  carry  water  over  depressions  which  would 
otherwise  have  to  be  crossed  by  flumes  or  similar  structures. 
Since  methods  of  building  suitable  pipes  of  wood  have  been 
introduced  in  the  West  this  form  of  structure  has  come  into 
more  popular  use  because  of  its  relative  cheapness,  and  its  dur- 


MAIN    AND    DISTRIBUTING    PIPES  337 

ability.  More  recently,  particularly  on  the  works  of  the  Reclama- 
tion Service,  concrete  or  reinforced  concrete  pipes  have  been 
employed,  according  to  the  pressures  to  be  withstood. 

The  pipes  more  generally  used  are  of  cast  iron,  sheet  steel 
or  iron,  wood,  cement,  vitrified,  concrete  or  reinforced  concrete, 
according  to  the  amount  of  pressure  which  they  may  have  to 
withstand  and  the  relative  cost  of  the  various  materials  in  the 
locality  in  which  they  are  to  be  used.  The  pipes  in  more  general 
use  range  from  4  to  60  inches  in  diameter,  or  in  extreme  cases 
an-  even  larger,  though  it  has  usually  been  found  desirable  to  use 
two  pipes  when  the  volumes  to  be  carried  call  for  excessive 
dimensions  (Art.  246).  Cast-iron  pipe  should  be  used  only 
under  great  heads  of  pressure,  exceeding  say  200  feet.  Sheet 
metal  or  reinforced  concrete  pipe  has  generally  been  employed 
for  pressure  between  50  and  200  feet,  and  for  lower  pressures 
down  to  20  feet  wooden  pipes,  and  below  this  cement  or  vitrified 
pipes.  Wooden  pipes  are  now  being  used  under  certain  con- 
ditions more  cheaply  and  satisfactorily  than  reinforced  concrete, 
sheet  iron  or  cast  iron  for  pressures  as  high  as  200  feet.  The 
controlling  considerations  governing  the  adoption  of  any  par- 
ticular material  must  invariably  be  the  cost  of  materials  at  the 
point  at  which  the  work  is  to  be  constructed,  the  expense  of  put- 
ting it  together,  the  durability  desired,  and  the  duty  to  be  per- 
formed. 

In  general  it  may  be  stated  that  in  most  of  the  arid  region 
cast  iron  is  more  expensive  than  the  other  forms  of  pipe,  owing 
to  its  great  weight  and  the  consequent  heavy  freight  charges, 
that  wood  is  cheapest  where  it  may  be  sawed  near  the  seat  of 
work,  and  that  otherwise  reinforced  concrete  or  terra-cotta  tile 
pipe,  depending  on  pressures,  will  be  cheapest  in  the  long  run 
because  most  durable.  Experience  gained  in  the  West  indicates 
that  the  life  of  a  wooden  pipe  well  constructed  and  properly 
tended  is  quite  as  long  as  that  of  well-constructed  and  asphaltum- 
coated  sheet-metal  pipes.  It  may  be  expected  under  favorable 
conditions  to  have  a  life  of  at  least  forty  years,  though  the  least 
carelessness  in  preventing  oxidation  may  cause  it  to  rust  and 
become  worthless  in  a  few  years.  Reinforced  concrete  and 


338      APPLICATION    OF    WATER,    AND   PIPE    IRRIGATION 

vitrified  tile  pipes  undoubtedly  have  by  far  the  longest  life  and 
require  the  least  attention  and  repairs. 

273. — Flow  of  Water  in  Pipes. — The  formulas  for  the  flow 
of  water  in  pipes  are  practically  the  same  as  those  given  in  Chap. 
VI  for  the  flow  of  water  in  open  channels,  modified  by  friction 
due  to  the  pressure  under  which  the  pipe  may  be  placed.  "Water 
will  seek  its  own  level,"  and  as  a  result  of  this  well-known  law 
water  in  a  pipe  which  may  be  depressed  to  as  great  an  amount 
as  its  resistance  to  pressure  will  stand  will  rise  in  the  further 
arm  of  the  pipe  to  the  level  of  its  source  if  it  be  allowed  to  stand 
quietly  within  the  pipe  without  motion.  The  moment  that 
motion  or  flow  takes  place  it  becomes  necessary  to  overcome  the 
resistance  due  to  the  friction  of  the  water  against  the  walls  and 
bends  of  the  pipe,  and  this  balance  of  pressure  must  be  obtained 
by  shortening  its  lower  or  discharging  arm  in  order  that  the  source 


FIG.  130. — Flow  of  Water  in  Pressure  Pipes. 

may  be  at  a  greater  height  than  the  point  of  discharge  by  the 
head  necessary  to  overcome  the  resistance  due  to  friction. 

The  velocity  and  discharge  of  a  pipe  are  dependent  not  only 
on  the  head  or  pressure  for  a  given  diameter,  but  also  upon  the 
frictional  resistance  which  the  interior  of  the  pipe  offers  to  the 
flow  of  water.  Accordingly  the  discharge  for  a  given  head 
may  be  increased  for  the  same  diameter  of  pipe  by  using  a  pipe 
with  smoother  lining  with  the  straightest  possible  alignment 
and  fewest  obstructions  to  flow  in  the  way  of  bends  and  joints. 
In  conducting  water  through  pipes  from  storage  reservoirs  account 
must  always  be  taken  of  the  reduction  of  pressure  in  the  pipe  due 
to  the  lowering  or  draining  of  the  water  from  the  reservoir,  and 
such  pipes  should  always  be  calculated  on  a  basis  of  the  pressure 


FORMULAS   OF   FLOW   IN    PIPES  339 

due  to  the  height  of  their  inlets,  and  not  to  the  height  of  water  in 
the  reservoir. 

Should  the  pipe  rise  at  any  point  above  the  hydraulic  grade- 
line  (BE,  Fig.  130),  or  should  it  have  vertical  bends  of  any  con- 
siderable height,  air  will  accumulate  at  the  summit  of  these 
bends  at  A.  This  air  is  compressed  from  one  side  by  the  head 
/*,  and  on  the  other  side  by  the  head  H;  then  if  h  =  H  and  the 
surface  of  the  water  at  D  does  not  meet  the  outlet  of  the  pipe  E, 
there  will  be  no  discharge.  Under  less  extreme  cases  the  dis- 
charge will  be  greatly  reduced,  and  it  is  therefore  necessary, 
where  there  are  such  vertical  bends  in  pipes,  to  insert  ventilators, 
or  air-valves  as  they  are  called,  to  release  the  air-pressure  at  such 
points.  Likewise  at  the  lowest  point  in  a  pipe  crossing,  say  a 
ravine,  at  the  point  r,  mud,  dirt,  and  other  obstructions  are  apt 
to  accumulate,  and  it  is  necessary  to  insert  there  mud -valves 
or  blow-offs  for  clearing  the  pipes  of  such  obstructions. 

274.  Formulas  of  Flow  in  Pipes. — If  there  were  no  resist- 
ance to  the  flow  in  pipes,  due  to  friction  or  pressure,  the  veloc- 
ities of  flow  would  be  similar  to  those  for  falling  bodies.  Ex- 
perience has  shown,  however,  that  velocity  of  flow  in  pipes  is 
equal  to  only  two-thirds  of  the  height,  the  remaining  third  being 
lost  in  overcoming  the  resistance  to  flow  of  water  in  entering 
the  pipe;  hence  we  have  the  formula 

.M 

~^~T: 

in  which  g  is  the  acceleration  due  to  gravity  or  32.2  feet,  and 
h  is  the  head  or  height  of  fall. 

One  of  the  controlling  factors  in  determining  the  flow  of 
water  through  pipes  under  pressure  is  the  hydraulic  grade-line, 
which  is  a  straight  line  drawn  from  the  entry  to  the  exit  of  the 
pipe  (BE,  Fig.  130).  Water  flowing  through  a  pipe  which  has 
several  vertical  bends  in  it  may  rise  nearly  to  the  level  of  this 
hydraulic  grade-line,  though  the  pipe  should  never  except  under 
the  most  unfavorable  circumstances  rise  in  any  portion  of  its 
length  above  this  line,  otherwise  there  will  be  'a  decided  loss  of 
pressure  at  this  point  and  a  diminished  flow  below  it,  calling 


340      APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

for  an  increased  diameter  from  that  point  on  to  carry  the  dis- 
charge required. 

Where  the  vertical  bends  in  a  pipe  are  kept  well  below  the 
hydraulic  grade-line  or  where  the  pipe  is  practically  in  the  grade- 
line,  in  other  words,  when  its  alignment  is  straight,  it  will  be 
under  little  or  no  pressure,  and  the  formulas  of  flow  of  water 
in  open  channels  are  directly  applicable  to  all  computations 
necessary  to  determine  the  velocity  and  discharge  in  such  pipes. 
These  formulas  are  given  in  Chapter  VI,  and  may  therefore 
be  used  in  computing  the  discharges  and  other  factors  required 
in  designing  pipes  which  are  not  under  pressure. 

There  are  many  formulas  for  the  flow  of  water  in  pipes  under 
pressure,  notable  among  which  are  those  of  Weisbach,  D'Arcy, 
Flynn,  and  others  whom  it  will  be  unnecessary  to  mention  here. 
Nor  is  it  desirable  in  such  a  work  to  discuss  the  theory  of  such 
formulas.  These  subjects  are  fully  treated  in  many  accessible 
publications,  among  which  are  those  of  Weisbach,  Fanning, 
Bovey,  and  Flynn.  For  the  purposes  of  this  work  it  is  sufficient 
to  give  but  a  few  of  the  simpler  of  such  formulas,  and  the  neces- 
sary tables  to  aid  in  their  use.  The  most  satisfactory  modifica- 
tion of  the  more  abstruse  formulas  are  those  published  by  Mr. 
P.  F.  Flynn  in  private  pamphlets,  in  the  Transactions  of  the 
Technical  Society  of  the  Pacific  Coast  and  in  his  admirable 
treatise  on  ''Irrigation  Canals  and  other  Irrigation  Works," 
and  these,  with  abbreviated  tables,  are  given  in  the  following 
article. 

275.  Tables  of  Flow  in  Pipes  With  and  Without  Pressure.— 
The  Chezy  modification  of  Kutter's  formula  given  in  Art.  78, 

~,     ........     (2) 


is  really  the  most  satisfactory  which  can  be  used  to  express 
flow  in  pipes  without  pressure.  This  formula  is  sufficient  only 
for  particular  conditions  of  pipe  surface,  unless  the  value  of  C 
be  made  to  include  the  coefficient  of  roughness  and  other  modify- 
ing elements,  according  to  Kutter's  method.  So  considering  it 
here,  as  was  done  in  the  case  of  flow  in  open  channels,  the  tables 
given  in  Art.  77  then  furnish  the  material  from  which  to  com- 


TABLES    OF   FLOW    IN    PIPES  341 

pute  nearly  all  of  the  elements  of  flow  in  pipes  either  clean  or 
tuberculated. 

The  D'Arcy  formula  for  flow  in  clean  pipes  is 

* 


.  00000162 
^.00007726  +  -    —  -  --  1 

The  value  of  the  coefficient  in  this  formula  depends  on  the 
hydraulic  mean  depth  r,  and  is  not  affected  by  slope  as  is  the 
case  with  Kutter's  formula.  D'Arcy's  formula  is  based  on 
careful  experiments  made  with  clean  pipes  and  is  therefore  quite 
accurate  for  pipes  of  moderate  diameter,  but  not  for  pipes  of 
large  diameter.  Kutter's  formula,  on  the  other  hand,  is  derived 
not  only  from  experiments  with  small  but  also  with  very  large 
channels;  and  as  it  takes  into  consideration  the  roughness  of 
surface  as  well  as  the  slope,  it  agrees  more  accurately  with  the 
actual  discharge  than  does  D'Arcy's  for  large  pipes. 

Flynn  has  modified  D'Arcy's  formula  (3)  to  the  following 
simplified  form: 

„-   ISI'x  V*       ....      (4) 


He  has  also  taken  D'Arcy's  formula  for  flow  in  old  cast-iron 
pipes  badly  tuberculated,  and  from  it  has  derived  the  simplified 
form 

* 


in  which  d  equals  the  diameter  of  the  pipe,  and  i  is  the  sign  of 
the  slope  or  fall  of  water  in  any  height  h,  divided  by  i,  which 
i£  the  horizontal  projection  of  the  hydraulic  grade-line  joining 
the  two  extremities  of  the  pipe.  It  may  be  further  stated  that  r, 
which  is  the  hydraulic  mean  depth,  is  equal  to  one-fourth  of 
the  diameter  in  the  case  of  circular  pipes.  These  formulas 
may  again  be  reduced  to  the  more  simplified  Chezy  form 

v  =  C\/~ri  and  Q  =  ACV~ri,     ....     (6) 
and  the  values  of  these  factors  have  been  tabulated  by  Mr.  Flynn 


342      APPLICATION    OF   WATER,    AND   PIPE   IRRIGATION 


in  such  form  as  to  aid  the  rapid  solution  of  all  problems  relating 
to  the  flow  of  water  in  pipes. 

In  orde*r  to  simplify  Kutter's  formula  for  computation  of 
velocity  of  flow  in  pipes  under  varying  conditions  of  roughness 
and  diameter,  Mr.  Flynn  reduces  it  to  the  following  form,  after 
computing  Tables  XVIII  and  XIX  to  facilitate  its  use : 

K 

\/ff.    :      -      .      (7) 

The  value  of  the  coefficient  C  for  new  iron  pipes  of  36  to 
72  inches  diameter  ranges  between  100  and  115  and  changes 
little  with  changes  of  velocity.  For  such  pipes  tar-coated  the 
value  of  n  may  be  taken  as  .012  to  .015  (see  Art.  ooo).  For 
wooden-stave  pipe  values  of  C  from  no  to  125  have  been  ob- 

TABLE  XVIII. 

VALUES  OF  K  FOR  USE  IN  FLYNN'S  MODIFICATION  OF  KUTTER'S 

FORMULA. 


n 

K 

n 

K 

n 

K 

n 

K 

n 

K 

.009 
.010 
.Oil 

245-63 

225.51 

209.05 

.012 

.013 

.014 

195-33 
183.72 

J37-77 

-OI5 
.016 
.017 

165.14 
157.60 
150.94 

.018 
.019 
.020 

145  -03 
139-73 
134.96 

.021 

.022 

.023 

i3°-6'5 
126.73 
124.90 

TABLE  XIX. 

VALUES   OF   V~r    FOR   CIRCULAR   PIPES   OF  DIFFERENT 
DIAMETERS. 


Diameter. 

V7 

Diameter. 

VT 

Diameter. 

\/7 

ft.          in. 

in  feet. 

ft.         in. 

in  feet. 

ft.         in. 

in  feet, 

5 

-323 

2 

.707 

4            4 

.041 

6 

-354 

2                2 

-736 

4           8 

.080 

8 

.408  ' 

2            4 

.764 

5 

.118 

10 

-456 

2                6 

.790 

5           4 

-155 

.500 

2               8 

.817 

5          8 

.190 

2 

-540 

2             IO 

.842 

6 

.225 

4 

-577 

3 

.866 

6           6 

-275 

6 

.612 

3           4 

-9J3 

7 

J-323 

8 

.646 

3           8 

-957 

7          6 

1.369 

10 

.677 

4 

i  . 

8 

1.414 

SHEET-IRON   AND    STEEL    PIPES 


343 


TABLE  XX. 

AREAS,    ETC.,    OF    CIRCULAR    PIPES    OF    DIFFERENT    DIAMETERS 

AND    UNDER    PRESSURE. 
Based  on  D'Arcy's  formula  of  flow  through  clean  cast-iron  pipes,  in  which 

v  =  cV~r  X  \^T  and  Q  =  AC\Tr  X  \/7 
Area  in  square  feet  =  A;  also,  C\/~7  and  AC\/ r. 


Diam. 

A 

cvV 

AC\/7 

Diam. 

A 

CV7 

AC\f* 

ft.       in. 

sq.ft. 

ft.       in. 

sq.  ft. 

I 

.005 

ii.  61 

.063 

2          4 

4.276 

85.39 

365 

I* 

.OI2 

15-58 

.191 

2            8 

5.585 

9L51 

5" 

2 

.021 

[8.96 

-413 

3 

7.068 

97.17 

686 

3 

.049 

24-63 

1.208 

3         4 

8.726 

IO2 

895 

4 

.087 

29-37 

2.563 

3         8 

10.559 

107 

1136 

6 

.  196 

37-28 

7.306 

4 

12.566 

112 

1414 

8 

•349 

43-75 

15.270 

4          4 

14-748 

117 

1729 

10 

-545 

49-45 

26.952 

4         8 

17.104 

121 

2082 

.785 

54.65 

42.918 

5 

19-635 

126 

2476 

2 

1.069 

59-34 

63.435 

5         4 

22.340 

130 

2912 

4 

1.396 

63-67 

88.886 

5         8 

25.220 

'34 

3388 

6 

1.767 

67-75 

119.72 

6 

28.274 

138 

3912 

8 

2.182 

71.71 

156.46 

6        6 

33-183 

144 

4782 

10 

2.640 

75-3 

198 

7 

38-485 

149 

5757 

2 

3-142 

78.8 

247 

7         6 

44-179 

'54 

6841 

2             2 

3.687 

82.1 

302 

8 

50.266 

160 

8043 

tained  with  velocities  of  2  to  5  feet  per  second  in  pipes  44  to  72 
inches  in  diameter,  the  corresponding  values  of  n  being  from 
.on  to  .014. 

276.  Sheet-iron  and  Steel  Pipes. — Sheet-metal  pipes  were 
first  used  for  conveying  water  under  pressure  for  hydraulic  min- 
ing in  the  Far  West,  and  when  the  people  of  that  region  turned 
their  attention  to  agriculture  they  immediately  came  into  favor 
for  conveying  irrigation  water.  There  aje  several  varieties  and 
makes  of  these  pipes  constructed  either  of  iron  or  steel,  and  the 
prices  for  either  are  about  the  same.  Steel  is  preferable  to  wrought 
iron  chiefly  for  great  pressures,  since  for  lesser  pressures  its 
greater  strength  than  wrought  iron  requires  such  a  reduction 
in  its  thickness,  if  this  strength  is  to  be  utilized,  as  would  render 
it  liable  to  collapse.  Its  surface,  however,  is  more  smooth  and 
less  liable  to  scale  when  bent.  Wrought  iron,  on  the  other  hand, 
is  more  rigid  because  of  requiring  greater  thickness.  It  is  there- 


344      APPLICATION    OF   WATER,    AND   PIPE    IRRIGATION 


TABLE  XXI. 

AREAS,    ETC.,    OF    CIRCULAR    PIPES    OF    DIFFERENT    DIAMETERS 

AND    UNDER    PRESSURE. 

Based  on  D'Arcy's  formula  for  flow  of  water  through  old  cast-iron  pipes,  lined 
with  deposit,  in  which  v  =  £v  r  X  \/  *  and  Q  =  AC\/  r  ; 
Areas  in  square  feet  =  A ;  also,  Cv  r  and  A  Cv  r. 


Diam. 

A 

Cx/7 

ACVr 

Diam. 

A 

cV7 

ACVr 

ft.       in. 

sq.  ft. 

ft.       in. 

sq.   ft. 

I 

.005 

7.81 

.042 

2          6 

4.909 

59-45 

292 

I* 

.OI2 

10.48 

.128 

2            8 

5-585 

6i.55 

344 

2 

.022 

I2-75 

.278 

2           10 

6-305 

63-49 

400 

3 

.049 

16.56 

.813 

3 

7.068 

65-35 

462 

4 

.087 

J9-75 

r-725 

3         4 

8.726 

69 

602 

6 

.196 

25.07 

4-915 

3         8 

10  -599 

72.40 

764 

8 

-349 

29-43 

10.27 

4 

12.566 

75-7 

951 

10 

-545 

33-26 

18.13 

4         4 

14.748 

78.9 

1163 

-785 

36.75 

28.87 

4         8 

17.104 

81.9 

1400 

2 

1.069 

39-9i 

42-67 

5 

J9-635 

84.8 

1665 

4 
6 

1.396 
1.767 

42-83 

45-57 

59-79 
8o-53 

5         6 
6 

23-758 
28.274 

89.1 
93-i 

2116 
2632 

8 

2.182 

48.34 

105-25 

6        6 

33-183 

96-9 

3216 

10 

2.640 

50.66 

!34 

7 

38-485 

100.6 

3872 

2 

3-142 

52.96 

1  66 

7        6 

44-179 

104.1 

4602 

2            2 

3.687 

55-26 

204 

8 

50.266 

107.6 

54io 

2         4 

4.276 

57-44 

246 

• 

TABLE  XXII. 

VALUES    OF    C\/7   FOR    VARIOUS    DIAMETERS    AND     COEFFICIENTS 
OF   ROUGHNESS   H,    FOR   CIRCULAR   PIPES    FLOWING   FULL. 

Based  on  Flynn's  modification  of  Kutter's  formula,  v  =  C\/  r  X  \/  i  and 
Q  = 


d 
ft.       in. 

n=.bn 
CVT 

n=.oi3 

cV7 

H=.OI7 

CVT- 

d 
ft.       in. 

n=.on 

cV7 

n=.OI3 

CVT 

«=.oi7 

cV7 

6 

3°-9 

24.6 

16.98 

3          4 

124 

103 

75 

8 

38.7 

31 

21.6 

3         8 

132 

no 

80 

10 

45-8 

36-9 

25.8 

4 

140 

116 

86 

52.8 

42.6 

3° 

4         4 

148 

123 

9i 

2 

59-i 

47-8 

33-9 

4         8 

J55 

129 

95 

4 

65.2 

52-9 

37-6 

5 

163 

135 

IOO 

6 

7i 

57-8 

4i-3 

5         6 

i73 

144 

1  08 

8 

76.8 

62.6 

44-9 

6 

183 

153 

114 

10 

82.1 

67 

48.2 

6        6 

J93 

161 

121 

2 

87.4 

71.4 

5i-6 

7 

202 

169 

127      ' 

2         4 

97-3 

79-9 

57-9 

7         6 

211 

177 

133 

2            8 

107 

87-9 

64 

8 

220 

184 

139 

3 

116 

95 

70 

SHEET-IRON    AND    STEEL   PIPES  345 

fore  less  liable  to  be  dented  or  otherwise  injured,  and  being  more 
porous  it  takes  the  asphalt  coating  better  than  does  steel.  The 
plates  from  which  these  pipes  are  made  are  usually  annealed, 
and  in  the  case  of  wrought  iron  a  tensile  strength  of  about  45,000 
pounds  per  square  inch  and  in  steel  about  60,000  pounds  per 
square  inch  is  called  for. 

There  are  many  makes  of  pipe,  the  more  prominent  of  which 
are  lap-welded,  converse  lock- jointed  pipe;  straight,  double- 
riveted,  and  spiral-riveted  pipe.  These  are  made  of  plate  ranging 
from  18  B.W.  gauge  down  to  No.  10  gauge,  and  even  thicker. 
Safe  working  stresses,  in  pounds,  for  the  various  gauges  of  metal 
more  usually  employed  are  as  follows: 

No.  Thickness.  Pounds  Square  Inch. 

16 !...        .16  6,000 

14 08  7o°° 

12 ii  g,ooo 

10 14  12,000 

iV-  -I0  14,000 

Straight-riveted  pipes  are  double-riveted  along  the  seams, 
and  as  delivered  several  lengths  are  riveted  together  or  lap- 
welded,  making  the  section  as  delivered  from  20  to  25  feet  in 
length.  The  distance  apart  between  rivets  in  the  rows  varies 
from  .33  to  .40  inch,  and  the  distance  between  any  two  rows  is 
about  f  of  an  inch.  Spiral-riveted  pipe,  as  its  name  implies, 
is  made  by  curving  the  plates  spirally  into  a  cylindrical  form, 
and  it  is  believed  that  this  method  of  riveting  gives  a  little  added 
stiffness,  owing  to  the  manner  in  which  the  riveting  and  the  seams 
are  disposed  around  the  circumference  of  the  pipe.  Laminated 
pipe  is  made  by  rolling  together  and  uniting  at  the  edges  two 
sheet-metal  plates  each  of  half  the  thickness  necessary  for  an 
ordinary  pipe.  The  inner  shell  is  telescoped  into  the  outer  while 
immersed  in  hot  asphalt,  thus  making  a  barrier  to  corrosion. 

All  sheet- metal  pipes  depend  for  their  length  of  life  on  the 
resistance  to  rust  of  the  asphalt  coating  given  them.  This  coating 
has  a  thickness  of  £  to  7V  of  an  inch,  and  is  made  as  nearly  im- 
pervious as  possible  on  both  the  inner  and  outer  surfaces.  The 
composition  of  this  coating  is  various  proportions  of  asphaltum 


346      APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

fluxed  with  crude  oil  and  heated  nearly  to  burning-point.  In 
this  hot  fluid  the  pipes  are  inserted.  There  is  a  decided  difference 
in  various  makes  of  pipe  as  to  the  amount  and  character  of  the 
flux  used  with  the  asphaltum,  and  each  maker  has  his  own  special 
variety  and  mode  of  application.  Well-coated  pipes  have  been 
frequently  examined  which  have  remained  clean  for  15  to  25  years. 
On  the  other  hand,  uncoated  pipes  rapidly  corrode,  thus  dimin- 
ishing their  carrying  capacity  as  much  as  75  per  cent  for  6-inch 
pipes  and  less  for  larger  diameters.  Tar-coated  pipes  15  years 
old  and  48  inches  diameter  have  had  their  carrying  capacity  re- 
duced 25  per  cent  by  tuberculation. 

277.  Wooden-stave  Pipes. — There  are  a  number  of  varie- 
ties of  this  make  of  pipe,  among  the  first  to  find  favor  being 
that  known  as  the  Colorado  wooden  pipe,  the  invention  of  Mr. 
C.  P.  Allen  of  Denver.  There  have  since  been  put  on  the  mar- 
ket various  modifications  of  this  pipe,  each  possessing  special 
advantages.  The  chief  differences  in  these  various  forms  of  pipe 
consist  in  the  method  of  binding  the  edges  of  the  staves  together, 
that  is,  the  form  of  the  groove  or  lug  with  which  they  meet  and  the 
mode  of  uniting  or  fastening  the  ends  of  the  metal  binding- 
rods.  These  pipes  are  made  in  sizes  from  10  inches  up  to  72 
inches  in  diameter,  while  even  larger  diameters  might  be  used  if 
desired. 

The  walls  of  these  pipes  are  of  wooden  staves  bound  together 
by  steel  bands.  These  staves  are  shaped  on  the  broad  sides  to 
cylindrical  circles  and  the  edges  to  true  radial  lines,  so  that  when 
put  together  they  form  a  perfect  cylindrical  pipe.  To  join  the 
ends  of  the  staves  a  thin  metallic  tongue  is  in  some  cases  inserted, 
this  being  a  trifle  longer  than  the  width  of  the  stave  and  cutting 
into  the  two  adjoining  staves.  The  confining  bands  are  of  round 
or  flat  iron  or  steel  f  to  f  inch  in  diameter,  according  to  the 
pressures  to  be  withstood  and  the  diameter  of  the  pipe,  and  are 
shipped  from  the  factory  as  rods.  These  rods  are  provided  at 
one  end  with  a  square  head,  at  the  other  with  a  thread  and  nut. 
They  are  bent  on  the  ground  on  a  bending  table  to  the  proper 
form,  and  are  coated  with  mineral  paint  or  asphaltum  varnish 
and  cut  about  6  inches  longer  than  the  outside  circumference  of 


CONSTRUCTION   OF    WOODEN    PIPE   LINES  347 

the  pipe,  on  which  they  are  slipped  loose.  As  the  construction 
of  the  pipe  progresses  these  binding-rods  are  screwed  up  gradually 
until  brought  to  a  uniform  tension  on  the  whole  length  of  the  pipe. 

In  some  forms  of  pipe  the  coupling  or  saddle  in  which  the 
rod  ends  are  fixed  is  of  cast  iron.  In  one  the  threaded  portion  of 
the  binding-rod  is  upset  and  an  eye  formed  at  the  other  end  which 
fits  into  a  special  casting,  and  instead  of  a  metallic  tongue  at  the 
stave  ends,  a  flat  V-shaped  groove  is  used,  a  similar  groove  being 
also  employed  on  the  edges  of  the  staves. 

The  best  materials  from  which  to  make  such  pipes  are  Oregon 
pine  and  California  redwood.  The  latter  has  a  great  advantage 
over  any  other,  in  that  it  has  a  great  crushing  strength  which 
prevents  rounded  bands  from  penetrating  the  wood  in  case  of 
excessive  strain  due  to  the  swelling  of  the  wood  when  saturated. 
The  staves  are  usually  prepared  for  the  larger  diameter  of  the 
pipes  from  carefully  selected  2  X  6-inch  joists,  which  are  dressed 
down  less  than  one-half  an  inch  in  either  direction.  The  dis- 
tances apart  of  the  binding-rods  vary  from  5  inches  apart  be- 
tween centers  under  great  pressures  up  to  12  inches  under  lesser 
pressures,  and  in  putting  these  pipes  together  the  staves  can  be  so 
dressed  and  the  binders  so  placed  as  to  accommodate  pipes  to 
moderate  curve  both  vertically  and  horizontally.  The  diameter 
of  the  pipes  may  be  reduced  during  construction  by  inserting 
tapering  staves  at  proper  places,  and  the  reduction  can  thus  be 
made  without  any  abrupt  change  of  diameter,  but  gradually. 

278.  Construction  of  Wooden  Pipe  Lines. — Wooden  pipe  lines 
should  be  so  aligned  and  located  as  to  be  kept  well  below  the 
hydraulic  grade-line  in  order  that  the  pipe  shall  not  only  be  kept 
full  of  water,  but  under  pressure  at  all  times,  otherwise  it  will 
rapidly  deteriorate.  Care  must  be  taken  in  aligning  a  wooden 
pipe  to  introduce  as  few  and  as  large  curves  as  possible,  owing 
to  the  difficulty  of  constructing  these.  After  the  staves  have  been 
dressed  they  must  be  kept  under  cover  to  avoid  warping  or 
checking.  Care  must  be  taken  in  tightening  the  binding  bands, 
for,  no  matter  how  tightly  these  may  be  fastened  when  the  pipe 
is  built,  they  will  be  comparatively  loose  within  a  couple  of  days, 
and  water  will  be  spurting  from  every  seam. 


348      APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

Experience  differs  as  to  the  desirability  of  burying  wooden- 
stave  pipes  in  the  earth,  and  of  coating  the  wood.  Pipes  which 
are  above  the  surface  are  exposed  to  destruction  from  fires. 
Such  coatings  as  coal-tar  and  asphaltum  only  increase  this  danger, 
and  in  general  this  class  of  coating  is  not  recommended.  For 
the  interior  of  flumes  and  of  pipes  asphaltum  has  certain  pre- 
servative advantages;  but  the  great  disadvantage  of  such  coating 
on  either  surface  is  that  it  prevents  free  soakage  of  the  wood  and 
the  passage  of  the  water  from  the  interior  to  the  exterior  of  the 
pipe,  for  on  the  constant  saturation  of  the  wood  is  largely  de- 
pendent its  preservation.  It  is  believed  that  wooden-stave  pipes 
above  ground,  kept  saturated,  will  last  longer  than  the  metal 
binding-rods  underground. 

The  tensile  strength  of  the  binding-rods  is  affected  (i)  by 
the  pressure  in  the  pipes;  (2)  by  the  pressure  arising  from  the 
expansion  of  the  wood;  (3)  by  the  tensile  strength  of  the  rod 
itself;  and  (4)  by  the  compressive  strength  of  the  wood.  Mr. 
C.  K.  Bannister  gives  the  following  simple  formula  for  deter- 
mining the  distance  between  adjacent  bands  : 
Let  d  =  distance  in  inches  between  two  bands; 

/  =  maximum  tensile  strength  of  each  band  in  pounds  ; 
p  =  pressure  of  water  in  Ibs.  per  sq.  in.  measured  at  bot- 

tom of  pipe; 

r  =  internal  radius  of  pipe; 

C  =  coefficient  to  allow  for  strain  caused  by  swelling  of 
wood;    also   includes  factor  of   safety   in  binding- 
rods. 
Then 


Practice  indicates  that  C  is  generally  equal  to  about  4  or  5  as  a 
factor  of  safety. 

In  some  cases  it  is  believed  desirable  to  anchor  inclined  wooden 
pipes  in  order  to  prevent  their  creeping.  More  recent  experi- 
ences indicate,  however,  that  where  such  pipes  are  carefully 
constructed,  and  where  their  ends  terminate  in  substantial  pen- 
stocks of  heavy  timberwork  or  masonry,  there  will  be  no  tendency 


REINFORCED    CONCRETE    PIPE 


349 


to  creep,  and  the  mode  of  construction  of  the  pipe  itself  creates 
a  stiff  shell  of  such  large  diameter  as  practically  to  prevent  any 
such  tendency. 

279.  Reinforced  Concrete  Pipe. — This  material  is  used  quite 
extensively  on  the  more  recent  works  of  the  Reclamation  Service 
for  pipe  culverts,  siphons,  etc.,  and  in  a  few  instances  for  long 
pressure  pipes.  The  most  notable  example  of  the  latter  use  is 
on  the  line  of  the  power  canal  of  the  Roosevelt  dam,  Arizona. 
At  the  crossing  of  Cottonwood  canyon  is  an  inverted  pressure 
pipe  250  feet  long  under  a  head  of  76  feet,  and  at  Pinto  Creek 


FIG.  131. — Travelling  Forms  for  Moulding  Concrete  Pipe. 

crossing  a  length  of  2130  ft.,  and  a  head  of  35  ft.  At  both  places 
are  two  lines  of  pipe  each  5  ft.  3  inches  inside  diameter,  with  a 
thickness  of  6  inches  and  7  inches  respectively,  at  the  two  cross- 
ings. Each  pipe  is  of  concrete,  that  at  Cottonwood  crossing 
being  reinforced  circumferentially  with  f-inch  rods  6  inches 
centers,  and  longitudinally  by  six  rods  of  f-inches  diameter. 
At  Pinto  crossing  the  reinforcing  rods  are  of  the  same  dimen- 
sions, spaced  and  3  inches  centers  circumferentially  and  with 
ten  rods  longitudinally. 

These  pipes  were  moulded  in  place  by  use  of  an  ingenious 
system  of  outside  detachable  steel  framework  with  wooden  lag- 


350      APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

ging  and  inner  travelling  form  called  an  "alligator,"  the  whole 
the  design  of  F.  Teichman.  The  plates  of  the  alligator  formed 
the  lower  semicircle  of  the  inner  mold,  the  upper  stationary  plates 
being  erected  over  the  slowly  moving  alligator  and  supported  on 
rails.  These  were  built  in  half  cylinders  bolted  to  those  pre- 
viously erected  so  as  to  form  a  rigid  upper  half  cylinder  of  70 
feet  length.  The  lower  half  cylinder  of  the  alligator  had  a  length 
of  about  24  feet,  beyond  which  it  sloped  for  10  feet  to  a  point. 

In  the  construction  of  concrete  pipe  for  sewers  in  Indianapolis, 
Ind.,  very  simple  collapsible  sheet-steel,  half -cylindrical  forms 
were  used.  The  lower  half  of  the  forms  consisted  of  short 
sections  about  3  ft.  long,  with  top  bracing.  The  upper  half  form 
was  over  50  feet  in  length  and  was  hauled  forward  by  block  and 
tackle  (Fig.  131). 

280.  Measurement  of  Flow  in  Pipes. — Where  water  is  pumped 
an  excellent  measure  of  the  volume  discharged  from  pipes  can  be 
obtained  by  noting  the  capacity  of  the  pump  per  stroke  and  the 
speed  and  time  of  running.  Otherwise  the  only  satisfactory 
method  of  directly  measuring  their  discharge  is  by  means  of  some 
of  the  various  patented  water-meters.  Measurement  by  com- 
putations depending  on  the  diameter  of  the  pipe,  head  of  water 
and  consequent  theoretic  velocity  is  not  at  all  satisfactory.  There 
are  a  number  of  water-meters  on  the  market,  nearly  all  of  which 
give  satisfactory  results,  though  some  of  them  are  apt  to  be 
clogged  by  sediment  in  turbid  waters  and  others  are  too  heavy 
and  cumbersome  or  too  expensive  to  be  satisfactorily  used  on 
irrigation  work,  except  where  water  has  an  extremely  high  value 
and  is  sold  by  careful  measure. 

Perhaps  the  form  of  water-meter  which  is  most  likely  to  find 
favor  among  irrigators  is  the  Venturi  meter,  the  invention  of 
Mr.  Clements  Herschel.  These  meters  are  made  in  all  sizes, 
from  those  suitable  for  measuring  pipes  a  few  inches  in  diam- 
eter up  to  meters  capable  of  utilization  on  pipes  6  or  8  feet  in 
diameter.  This  meter  consists  of  two  pipes  forming  the  tube, 
and  of  the  register.  The  former  consists  of  two  funnel-shaped 
pipes  of  different  tapers,  while  the  latter  is  a  delicate  electrical 
recording  apparatus  with  dials,  etc.,  which  registers  the  volumes 


MEASUREMENT    OF    FLOW    IN    PIPES 


351 


discharged  (Fig.  132).  This  meter  is  not  affected  by  water- 
hammer,  dirt,  sticks,  or  other  substances.  The  principle  on 
which  it  works  is  that  of  measuring  the  differences  of  pressure 
due  to  friction  in  passing  through  the  throat  of  the  pipe,  for  it  is 
well  known  that  the  pressure  is  less  at  the  throat  or  contraction 
than  at  the  up-stream  end.  A  peculiar  feature  of  this  instrument 
is  that  this  difference  in  pressure  does  not  produce  any  appreciable 
loss  of  head,  as  is  the  case  with  other  meters;  and  the  final  result  of 
the  principle  on  which  it  depends  for  its  action  is  summed  up  in 
the  rule  that  "the  faster  the  flow  of  the  water  through  the  Venturi 


Chart  Recorder 
continuously  Record* 
cubic  feet  per  second 


FIG.   132. — Venturi  Meter  and  Recording  Device  on  Lateral  Head. 

tube  the  greater  is  the  difference  in  pressure  at  the  up-stream  end 
and  at  the  throat  of  the  tube;  and  the  slower  the  flow  the  less  the 
difference  in  pressure."  Upon  this  principle  the  action  of  the 
meter  is  based,  and  by  utilizing  these  differences  of  pressure  the 
amount  of  flow  is  shown  by  the  register. 

Except  for  the  delicate  registering  apparatus  this  instru- 
ment is  not  necessarily  expensive.  It  consists  practically  of  a 
couple  of  cast-iron  pipes  moulded  to  fixed  shapes.  Cheaper 
forms  of  the  Venturi  meters  are  being  constructed  for  use  in  meas- 
uring sewage  of  towns,  and  still  cheaper  forms  are  being  de- 
signed in  brick  and  cement,  and  even  in  wood,  for  measuring 
the  discharges  in  open  as  well  as  closed  irrigating  channels. 


352       APPLICATION    OF    WATER,    AND    PIPE    IRRIGATION 

281.  Works  of  Reference.     Application  of  Water,  and  Pipe 
Irrigation. 

BOVEY,  HENRY  T.     A  Treatise  on  Hydraulics.     John  Wiley  &  Sons,  New  York, 

1895. 
FANNING,  J.  T.     A  Treatise  on  Water-supply  Engineering.     D.  Van  Nostrand  & 

Co.,  New  York,  1878. 
FINKLE,  F.  C.     Pipes  in  California  Irrigation.     Irrigation  Age,  Chicago,  Illinois, 

October,  1893. 
FLYNN,   P.    J.     Irrigation   Canals  and  other  Irrigation  Works.     San   Francisco, 

California,  1892. 
FORTIER,  SAMUEL,     Use  of  Pipes  in  Irrigation.     Irrigation  Age,  Chicago,  Illinois, 

July  and  August,  1893. 

—  Pipe  Irrigation.     Trans.  Am.  Soc.  Irr.  Engs.,  Denver,  Colorado,  1893. 

—  Conveyance  of  Water.      Water-supply  Paper  No.  43.     U.   S.   Geological 
Survey      Washington,  D.  C.,  1902. 

GOULD,   E.   SHERMAN.     Practical  Hydraulic   Formulas,   etc.     Engineering  News 

Publishing  Company,  New  York,  1894. 
HALL,  WM.   HAM.     Santa  Ana  Canal  of  the  Bear  Valley  Irrigation  Company. 

Trans.  Am.  Soc.  C.  E.,  vol.  33,  No.  2,  New  York,  1895. 

KING,  F.  H.     Irrigation  and  Drainage.     The  Macmillan  Co.     New  York,  1899. 
WEISBACH,  P.   J.,  and  Du  Bois,  A.   JAY.     Hydraulics  and  Hydraulic  Motors. 

John  Wiley  &  Sons,  New  York,  1889. 
WILCOX,  LUTE.     Irrigation  Farming.     Orange  Judd    &  Company,  New  York, 

1895. 


Part   III 
STORAGE    RESERVOIRS 


CHAPTER  XV 

LOCATION    AND    CAPACITY   OF    RESERVOIRS 

282.  Classes  of  Storage  Works. — A  storage  work  is  any  variety 
of  natural  or  artificial  impounding  reservoir  or  tank  for  the  saving 
of  flood  waters.     Storage  works  are  employed  to  insure  a  constant 
supply  of  water  during  each  and  every  season  regardless  of  the 
amount  of  rainfall.     They  may  be  classified  according  to  the 
character  and  location  of  the  storage  basin,  or  the  materials  and 
construction  of  the  retaining  wall  or  dam  which  closes  it.     Under 
the  former  classification  are: 

1.  Natural  lake  basins; 

2.  Reservoir  sites  on  natural  drainage  lines,  as  a  valley  or 
canyon  through  which  a  stream  flows; 

3.  Reservoir  sites  in  depressions  on  bench  lands; 

4.  Reservoir  sites  which  are  in  part  or  wholly  constructed 
by  artificial  methods. 

For  the  second  classification,  see  Art.  289. 

283.  Character  of  Reservoir  Site. — i.  If  situated  in  a  natural 
lake  basin,  a  short  drainage  cut  or  a  comparatively  cheap  dam 
or  both  may  give  a  large  available  storage  capacity.     Such  sites 
are  usually  the  cheapest,  costing  for  construction  as  low  as  20 
cents  per  acre-foot  stored,  and  in  unfavorable  cases  rarely  ex- 
ceeding $3  per  acre-foot. 

2.  The  most  abundant  reservoir  sites  are  those  on  natural 
drainage  lines,  though  these  are  usually  the  most  expensive  of 
construction  owing  to  the  precautions  necessary  in  building  the 
dam  to  provide  for  the  discharge  of  flood  water. 
23  353 


354  LOCATION   AND   CAPACITY   OF   RESERVOIRS 

3.  Almost  equally  abundant  are  those  reservoir  sites  found  in 
depressions  on  bench  or  plains  lands.     The  utilization  of  such 
basins  as  reservoir  sites  is  comparatively  inexpensive;  they  can  be 
converted  into  reservoirs  by  the  construction  of  a  deep  drainage 
cut  or  of  a  comparatively  cheap  earth  embankment,  or  both. 
Scarcely  any  provision  is  necessary  for  the  passage  of  floods.     The 
heaviest  item  of  expense  in  connection  with  such  sites  is  the  supply 
canal  for  filling  them  from  some  adjacent  source. 

4.  Artificial   reservoirs    are   occasionally   constructed   where 
water  is  valuable,  by  the  erection  of  an  earth  embankment  above 
the  general  surface  of  the  country  or  by  the  excavation  of  a  reser- 
voir basin  by  artificial  means.     Such  constructions  are  usually 
insignificant  in  dimensions,   as  the  expense  of  building  large 
reservoirs  of  this  kind  would  ordinarily  be  prohibitive. 

Shallow  reservoirs  should  not  be  constructed,  since  the  loss 
from  evaporation  and  percolation  is  proportionately  great,  and 
the  growth  of  weeds  is  encouraged,  where  the  depth  is  less  than 
seven  feet,  by  the  sunlight  penetrating  to  the  bottom. 

284.  Relation  of  Reservoir  Site  to  Land  and  Water-supply. 
— There  are  several  modifying  considerations  affecting  the  value 
of  the  reservoir  site.  Among  the  more  important  are : 

1.  The  relation  of  the  site  to  the  irrigable  lands ; 

2.  The  relation  of  the  site  to  its  catchment  basin  or  source 
of  supply; 

3.  The  topography  of  the  site; 

4.  The  geology  of  the  site. 

The  cost  of  water  storage  depends  chiefly  on  the  last  two, 
while  the  value  of  the  site  for  storing  water  and  the  possibility 
of  filling  the  reservoir  depends  on  the  first  two. 

In  considering  the  relation  of  the  reservoir  site  to  the  irri- 
gable lands,  the  former  should  he  situated  at  a  sufficient  alti- 
tude above  the  latter  to  allow  of  the  delivery  of  water  by  natural 
flow.  The  area  of  irrigable  lands  should  be  sufficient  to  make 
use  of  the  entire  amount  of  water  stored,  that  the  maximum 
return  may  be  derived  from  water  rates,  and  the  reservoir  should 
be  as  neaf  as  possible  to  the  irrigable  lands  in  order  that  the 
loss  in  transportation  shall  be  a  minimum.  It  not  infrequently 


TOPOGRAPHY   AND    SURVEY   OF    RESERVOIR    SITES       355 

happens,  however,  that  the  reservoir  is  of  necessity  located  at 
seme  distance  from  the  irrigable  lands,  thus  requiring  either  a 
long  supply  canal  or  that  the  water  be  turned  back  into  the  natural 
drainage  channel,  down  which  it  will  flow  till  diverted  in  the 
neighborhood  of  the  irrigable  lands.  This  is  very  wasteful  of 
water,  since  the  losses  by  absorption,  percolation,  and  evaporation 
are  great,  especially  if  the  bed  of  a  natural  channel  is  used  as  a 
portion  of  the  supply  line. 

As  related  to  the  source  of  supply,  the  reservoir  site  may 
be  on  a  perennial  stream  the  discharge  of  which  is  more  than 
sufficient  to  fill  it,  in  which  case  the  supply  is  assured.  It  may 
be  on  a  stream  the  available  perennial  discharge  of  which  is 
sufficient  to  fill  it  only  in  times  of  flood.  It  may  be  on  an  inter- 
mittent stream  subject  to  occasional  flood  discharges  of  sufficient 
volume  to  fill  the  reservoir  so  as  to  enable  it  to  tide  over  a  couple 
of  seasons  of  moderate  supply.  Or  the  reservoir  site  may  be 
situated  above  and  away  from  any  natural  drainage  line,  in 
which  case  it  will  receive  its  supply  either  by  a  canal  diverted 
from  some  perennial  stream  or  from  artesian  wells  or  springs. 

285.  Topography  and  Survey  of  Reservoir  Sites. — Knowing 
the  position  of  the  irrigable  lands,  a  careful  preliminary  survey 
should  be  made  of  the  entire  neighborhood  to  discover  all  possible 
reservoir  sites,  and  the  outlines  of  the  catchment  basins  of  each  of 
these  should  be  mapped,  while  stream  gauging  should  be  con- 
ducted and  examinations  and  inquiries  made  to  ascertain  the 
minimum  discharge  of  the  streams  and  their  flood  heights,  as  well 
as  the  amount  of  evaporation  and  percolation  (Chapters  III  and 
IV).  Having  determined  in  a  general  way  upon  the  location  of 
the  reservoir  site,  a  detailed  survey  of  it  should  be  made.  This 
can  ordinarily  be  best  done  by  means  of  a  plane  table.  The 
highest  possible  point  to  which  the  dam  may  reach  may  be  taken 
as  a  datum,  and  a  top  contour  run  out  closing  around  the  entire 
site.  A  main  traverse  should  then  be  run  through  the  lowest  line 
of  the  site  from  the  dam  to  the  extreme  end  where  it  will  connect 
with  the  top  contour.  Cross-section  lines  may  be  run  from  this 
with  the  plane  table,  and  the  topography  of  the  site  sketched  in 
5 -foot  contours  and  plotted  to  some  large  scale,  preferably  500  to 


356  LOCATION   AND    CAPACITY   OF   RESERVOIRS 

1000  feet  to  the  inch.  Where  the  country  is  open  the  site  may  be 
triangulated  from  one  side,  as  a  check  on  the  cross-section  lines, 
and  where  the  slopes  are  even  these  may  be  best  determined  by 
means  of  gradienter  lines  run  up  and  down  them  from  a  base 
contour.  Such  a  map  will  enable  the  engineer  to  determine  the 
capacity  of  the  reservoir  for  various  depths  of  water. 

To  calculate  the  storage  capacity  of  the  reservoir  the  area 
enclosed  by  each  contour  must  be  measured  on  the  map  with  a 
pi  ammeter,  and  the  mean  area  between  adjacent  contours  multi- 
plied by  the  contour  interval  will  give  the  volume.  The  sum  of 
all  the  volumes  between  successive  contours  will  be  the  full  capa- 
city of  the  reservoir.  There  is  quite  an  error  by  this  method  when 
the  slopes  are  flat,  in  which  case  the  prismoidal  formula  should 
be  used.  By  this  the  volumes  of  two  successive  intervals  in 

terms  of  three  areas  a,  b,  and  c  equals  (a  +  46  +  c)-,  where  a,  b, 

o 
and  c  are  the  two  end  and  intermediate  areas  and  d  is  the  contour 

interval.  The  available  volume  of  a  reservoir  is  always  less 
than  its  full  capacity  both  because  some  portion  is  below  the 
outlet  sluices  and  because  some  part  of  the  bottom  will  soon 
become  filled  with  sediment.  This  is  often  one-fifth  or  more 
of  the  height  of  the  dam,  though  a  far  less  proportion  of  the 
reservoir  content. 

Having  determined  the  elevation  of  the  outlet  sluices,  grade- 
lines  must  be  run  to  determine  the  route  of  the  canal  which  is 
to  carry  the  water  to  the  irrigable  lands,  also  to  ascertain  whether 
it  can  be  led  to  the  higher  or  more  arable  portion  of  such  lands 
(Art's.  137  to  139). 

The  dam  site  should  be  surveyed  in  greater  detail,  several 
possible  sites  being  cross-sectioned  and  mapped  in  i-foot  con- 
tours and  at  a  scale  of  50  to  100  feet  to  the  inch.  This  work 
should  be  done  with  transit  and  tape,  whereas  in  the  reser- 
voir survey  the  stadia  may  be  satisfactorily  employed  on  most 
of  the  cross-section  lines.  Several  test  pits  or  borings  should 
be  made  at  the  dam  site  to  determine  the  nature  of  the  foundation. 
Samples  of  rock,  clay,  etc.,  should  be  collected  and  tested  to 
determine  its  value  as  material  for  constructing  masonry  or 


EXPLORING    FOR    ROCK   FOUNDATION  357 

earth  dams.  With  such  a  knowledge  of  the  topography  of  a 
catchment  basin  and  of  the  reservo;  and  dam  sites  as  the  re- 
sulting map  and  data  will  give,  the  engineer  may  readily  compute 
the  cost  of  construction  of  dams  for  various  heights  as  well  as  the 
contents  of  the  reservoir  for  these  heights,  and  thus  determine 
what  height  of  dam  will  be  most  economic  of  construction,  for 
there  is  always  some  height  which  will  render  the  unit  cost  of 
storage  a  minimum. 

286.  Exploring  for  Rock  Foundation. — Three  methods  may 
be  employed  to  determine  the  depth  of  rock  foundation  at  a 
dam  site;  these  are,  in  inverse  order  of  their  merit:  i,  by  sound- 
ing-rods; 2,  by  sinking  open  shafts;  and,  3,  by  diamond  core- 
drill. 

The  first  method  consists  in  driving  or  churning  solid  steel 
sounding-rods,  each  10  or  more  feet  in  length,  and  f  to  i  inch 
diameter.  The  results  are  unsatisfactory,  as  friction  in  the  gravel 
bed  of  a  stream  is  such  as  to  limit  penetration  to  25  or  30  feet. 
They  are  incomplete,  as  the  rod  may  be  stopped  on  a  large  bowlder 
and  the  kind  and  texture  of  the  foundation  material  encountered 
cannot  be  examined.  Shaft-sinking  is  usually  quite  expensive, 
owing  to  the  cost  of  pumping  and  of  carrying  off  the  surface  or 
stream  water  in  a  flume  or  other  artificial  channel.  To  sink 
such  shafts  to  depths  greater  than  50  feet  will  cost  from  $20  to 
$30  per  foot  according  to  the  nature  of  the  material,  and  the  depth 
and  volume  of  surface  and  pumped  water  to  be  handled.  For 
shallow  depths  this  method  is  quite  satisfactory,  however,  as 
the  nature  of  the  foundation  rock  can  be  readily  examined. 

For  considerable  depths  the  method  which  is  by  all  odds 
the  most  satisfactory  and  cheapest  is  by  the  diamond  core-drill, 
since  the  result  is  certain  and  the  physical  and  chemical  proper- 
ties of  the  rocks  penetrated  can  be  tested.  Several  concerns 
make  and  sell  the  complete  apparatus. 

The  machinery  is  in  two  distinct  parts:  first,  a  pile-driving 
apparatus  for  putting  pipe  or  casing  down  through  quicksand 
or  earth;  the  pipe  is  afterwards  washed  out,  and  inside  of  it  the 
shaft  with  the  diamond  bits  is  operated.  The  second  part  is 
the  drilling  apparatus  proper.  The  machinery  is  very  light,  and 


35  8  LOCATION   AND    CAPACITY   OF   RESERVOIRS 

made  so  that  it  can  be  knocked  down  to  weights  that  will  admit 
of  the  sections  being  carried  on  the  backs  of  men.  The  hammer 
is  in  sections  and  can  be  increased  or  lessened  in  weight.  The 
bottom  section  is  cored  out  and  filled  with  wood,  so  that  the  blow 
of  the  hammer  will  not  abrade  the  head  of  the  pipe.  It  is  raised 
by  means  of  a  hand- winding  drum,  and  is  tripped  when  it  reaches 
the  tops  of  the  guides,  and  falls  upon  the  pipe.  The  maximum 
lift  is  nj  feet,  and  the  maximum  weight  190  pounds.  A  tool- 
steel  head  is  screwed  into  the  top  of  the  drive-pipe  for  the  hammer 
to  fall  upon. 

The  pipe  is  shod  at  its  lower  end  with  a  tool-steel  shoe,  which 
is  thicker  and  heavier  than  the  pipe,  but  equal  to  it  in  interior 
diameter.  The  size  of  the  pipe  used  is  3J-inch,  2 J-inch,  and  2-inch 
extra-heavy  screw-pipe,  with  extra-heavy  couplings  which  have 
bevelled  corners.  The  smaller  diameter  pipe  is  in  each  case  made 
to  fit  into  the  larger  diameter  if  required.  It,  however,  requires 
a  special  make  of  2^-inch  pipe  to  go  inside  of  the  3J-inch  pipe. 
The  pipe  is  driven  through  the  sand  and  gravel  until  bed-rock 
is  reached.  This  is  indicated  by  the  refusal  of  the  pipe  to  go 
any  farther  under  driving.  The  pipe  is  cut  in  5 -foot  sections, 
and  as  it  is  driven  into  the  ground  new  sections  are  put  on  until 
the  desired  length  is  reached.  When  the  drive-pipe  has  reached 
bed-rock,  what  is  known  as  a  chopping-bit,  which  is  a  bit  with 
openings  for  water  to  flow  through  its  point,  and  to  which  is 
screwed  a  f-inch  pipe,  is  worked  into  the  drive-pipe.  The  top 
of  this  f-inch  pipe  is  connected  with  a  small  double-action  hand 
force-pump  by  a  hose. 

The  chopping-bit  is  churned  around  in  the  sand  which  is 
inside  of  the  drive-pipe,  and  the  water  which  is  under  pressure 
is  discharged  through  the  point  of  the  chopping-bit,  and  floats 
the  loosened  sand  out  over  the  top  of  the  drive-pipe.  In  this 
manner  a  hole  can  be  readily  cleaned  to  depths,  as  great  at  130 
feet  of  sand  and  small  gravel. 

The  diamond  drilling  machinery  is  put  to  work  when  the 
drive-pipe  is  cleaned  out,  and  its  use  may  demonstrate  that, 
instead  of  being  on  a  bed-rock,  the  drive-pipe  has  stopped  upon 
a  bowlder.  As  soon  as  the  diamond  bit  passes  through  a  bowlder 


GEOLOGY   OF   RESERVOIR    SITES  359 

it  drops,  which  is  an  indication  that  bed-rock  has  not  been  reached. 
The  diamond  drill  is  then  drawn  and  four  or  five  sticks  of  giant 
powder  are  lowered  through  the  pipe  to  the  bowlder.  The  drive- 
pipe  is  then  pulled  up  four  or  five  feet,  and  the  powder  is  dis- 
charged by  means  of  an  electric  firing-batter)-.  This  shatters 
the  rock,  and  the  drive-pipe  may  then  be  forced  through  the 
splintered  bowlder. 

Such  a  machine  is  capable  of  drilling  200  feet  into  solid  rock. 
It  is  operated  by  hand,  six  men  being  necessary  to  handle  it 
and  the  pipe.  In  soft  rock  it  will  make  from  10  to  20  feet  per 
day,  and  in  hard  rock  from  5  to  10  feet.  The  cost  of  diamond 
core-drilling  ranges  from  $i  to  $3  per  foot,  according  to  hardness 
of  rock  and  locality,  and  including  cost  of  plant  where  several 
deep  holes  are  sunk. 

287.  Geology  of  Reservoir  Sites.— Having  ascertained  the 
desirability  of  the  reservoir  site  topographically  and  hydro- 
graphically,  a  few  test  borings  or  trial  pits  should  be  sunk  at 
various  points  on  the  reservoir  basin,  in  addition  to  those  at  the 
dam  site,  to  ascertain  the  character  of  the  soil  and  the  dip  of  the 
strata  underlying  the  proposed  reservoir.  The  geological  con- 
formation may  be  such  as  to  contribute  to  the  efficiency  of  the  re- 
servoir, or  it  may  prove  so  unfavorable  as  to  be  irremediable  by 
engineering  skill.  A  reservoir  site  which  is  situated  in  a  syn- 
clinal valley  as  shown  in  A,  Fig.  133,  is  the  most  favorable.  In 
this  the  strata  incline  from  the  hills  towards  the  lower  lines  of 
the  valley,  and  any  water  which  may  fall  on  to  these  hills  will 
find  its  way  by  percolation  through  the  strata  into  the  reservoir, 
thus  adding  to  its  volume.  An  anticlinal  valley  is  the  least 
favorable  for  a  reservoir  site  (Fig.  133,  B).  In  such  a  valley  as 
this  the  strata  dip  away  from  the  reservoir  site  and  would  permit 
of  the  escape  of  much  of  the  impounded  water,  percolation  through 
the  strata  leading  it  off  to  adjoining  valleys.  A  class  of  geologi- 
cal formation  intermediate  between  these  two  is  that  represented 
in  C,  Fig.  133,  in  which  the  valley  has  been  eroded  in  the  side 
of  strata  which  dip  in  one  direction.  Here  the  upper  strata 
lead  water  from  the  adjoining  hills  into  the  reservoir,  while  the 
strata  on  the  lower  side  tend  to  carry  it  off  from  the  reservoir 


36o 


LOCATION    AND    CAPACITY    OF   RESERVOIRS 


by  percolation.     In  such  a  case  it  is  probable  that  the  reservoir 
would  neither  gain  nor  lose. 

If  the  surface  of  the  proposed  reservoir  site  is  composed  of 
a  deep  bed  of  coarse  gravel  or  sand  or  even  limestone,  crevices 
in  the  latter  or  between  the  interstices  of  the  former  will  tend 
greatly  to  diminish  the  capacity  of  the  reservoir  by  seepage  from 
it.  Again,  the  geologic  formation  may  be  most  unfavorable, 
yet  if  the  surface  of  the  reservoir  site  be  covered  with  a  deep 


FIG.  133. — Diagrams  Illustrating  Geology  of  Reservoir  Site. 

deposit  of  alluvial  sediment  or  of  clay  or  dirty  gravel  or  other 
equally  impervious  material,  little  danger  may  be  apprehended 
from  loss  by  seepage. 

288.  Cost   and   Dimensions   of   some   Great   Storage   Reser- 
voirs.— In    Table    XXIII    are    given    the    capacities,    material, 
dimensions  of  dam,  and  cost  per  acre-foot  stored  of  some  of  the 
great  storage  reservoirs  which  are  used  for  purposes  of  irrigation. 

289.  Classes  of  Dams. — Dams  may  be  grouped  in  five  general 
classes,  according  to  the  materials  of  which  they  are  composed, 
as  follows : 

i.  Earth  dams  or  embankments. 


COST  AND   DIMENSIONS    OF    STORAGE   RESERVOIRS      361 


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362  LOCATION   AND   CAPACITY   OF   RESERVOIRS 

2.  Crib  or  rock-filled  timber  dams. 

3.  Loose-rock  or  rock-filled  dams. 

4.  Steel  dams. 

5.  Masonry  dams. 

These  may  be  combined  in  many  ways,  giving  rise  to  numerous 
varieties  merging  the  different  types. 

The  prime  essential  of  a  good  dam  is  that  it  shall  be  im- 
pervious and  stable,  since  its  function  is  to  prevent  the  passage 
of  water. 

The  choice  of  the  material  of  which  the  dam  shall  be  con- 
structed, whether  it  shall  be  of  earth,  masonry,  or  loose  rock, 
is  dependent  largely  upon  the  character  of  the  foundation,  the 
topography  of  the  site,  and  the  cost  of  transportation.  Earth 
dams  when  well  constructed  are  fully  as  substantial  as  those  of 
masonry,  and  in  many  cases  they  are  far  more  so.  In  countries 
subject  to  earthquakes,  or  where  the  rock  foundation  is  not 
thoroughly  homogeneous,  an  earth  dam  is  decidedly  preferable 
to  one  of  masonry.  They  are  usually  cheaper,  and  where  trans- 
portation is  expensive  they  are  very  much  cheaper.  Providing 
a  substantial  and  abundant  wasteway  of  a  sufficient  capacity 
to  carry  the  greatest  possible  flood  be  provided,  an  earth  dam 
is  generally  to  be  preferred  in  mild,  damp  climates.  In  warm, 
dry  climates  they  are  liable  to  dry  and  crack.  Where  the  founda- 
tion is  of  rock,  gravel,  or  hardpan,  or  where  earth  is  scarce,  rock 
abundant,  and  cement  costly,  a  loose-rock  dam  may  prove  the 
most  suitable  type.  For  dams  over  100  feet  in  height  on  solid 
rock  foundations  masonry  is  to  be  preferred,  as  earth  or  loose- 
rock  dams  are  nearly  as  expensive  when  transportation  is  cheap, 
and  are  more  liable  to  be  badly  built. 

A  substantial  masonry  dam  cannot  be  founded  on  loose  gravel 
or  soil;  an  earth  dam  should  rarely  be  founded  on  rock,  owing 
to  the  difficulty  of  making  a  tight  joint  between  it  and  the  earth 
unless  a  masonry  core-wall  is  used;  a  loose-rock  dam  may  be 
founded  on  rock,  earth,  or  almost  any  material. 


CHAPTER  XVI 

EARTH  AND  LOOSE- ROCK  DAMS 

290.  Earth  Dams  or  Embankments. — There  are  five  general 
types  of  earth  dams: 

1.  Earth  dams  having  a  central  core  or  wall  of  puddled  earth; 

2.  Earth  dams  having  a  central  core  of  masonry  or  wood ; 

3.  Earth  dams  built  up  in  layers  of  homogeneous  material, 
without  central  core  or  puddle  facing. 

4.  Earth  dams  with  selected  material  on  water  face  and  coarser 
material  on  lower  face. 

5.  Earth  dams  of  sand,  gravel,  etc.,  sluiced  into  position  by 
hydraulic  filling. 

291.  Causes  of  Failure  of  Earth  Dams. — An  earth  dam  may 
fail  (i)  from  lack  of  stability  of  cross-section;  (2)  from  disintegra- 
tion by  erosion  of  the  material  composing  it.     It  may  fail  from 
lack  of  stability  either  by  yielding  to  the  horizontal  pressure  of 
the  water  overturning  it,  or  by  sliding  on  its  base.     The  simplest 
form  of  calculation  clearly  demonstrates  what  is  fully  acknowl- 
edged by  all  engineers,  namely,  that  the  dam  will  not  be  destroyed 
by  overturning  or  revolving  about  its  lower  toe;   hence  the  only 
theory  as  to  its  destruction  is  that  it  may  slide  on  its  base.     The 
conditions   of   stability   will   be   unsatisfactory   when   the  hori- 
zontal component  of  the  water  pressure  against  the  bank  equals 
the  weight  of  the  latter  plus  the  vertical  pressure  exercised  by 
the  water  to  hold  it  down,  and  multiplied  by  the  coefficient  of 
friction.     Such  a  case  is  rarely  or  never  apt  to  occur.     In  point 
of  fact  such  structures  usually  fail,  not  by  overturning  or  sliding 
on  their  bases,  but  by  the  disintegration  of  their  particles  due 
to  the  erosive  action  of  water.     Failures  from  this  cause  are 
usually  due  (i)  to  insufficient  wasteway;    (2)  to  the  mode  of 
drawing  off  water  through  pipes  or  tunnels;    (3)  to  carelessness 


in  construction.  , 


363 


364  EARTH   AND    LOOSE-ROCK   DAMS 

292.  Dimensions  of  Earth  Dams. — When  subjected  to  the  con- 
tact of  percolation  water  earth  loses  a  certain  amount  of  its  sta- 
bility due  to  buoyancy,  and  therefore  it  is  customary  to  give  the 
inner  slope  of  an  embankment  a  greater  inclination  than  the  outer 
slope.  These  slopes  depend  on  the  character  of  the  material. 
When  the  outer  slope  will  stand  with  an  inclination  of  i  on  2  J  the 
inner  slope  should  be  i  on  3. 

The  interior  and  exterior  slopes  of  earth  dams  may  be  con- 
sidered as  planes  forming  together  an  angle  of  not  less  than 
90  degrees,  and  the  figure  should  be  so  formed,  in  order  to  in- 
crease its  stability,  that  lines  of  pressure  passing  from  the  in- 
terior faces  at  right  angles  may  fall  within  its  base.  As  one 
cubic  foot  of  rammed  earth  weighs  about  100  pounds  and  a 
cubic  foot  of  water  62^  pounds,  we  find  the  base  of  a  prism  re- 
sisting the  lateral  thrust  of  the  water  does  not  require  to  be  more 
than  two-thirds  of  the  depth  of  the  column  it  supports.  Hence 
all  quantities  above  that  are  due  to  the  natural  slopes,  the  stability 
of  the  dam,  and  the  prevention  of  percolation. 

In  large  works  it  is  frequently  a  matter  of  close  calculation 
to  determine  which  will  be  the  more  economical — dams  exclu- 
sively of  earth  or  those  whose  inner  slopes  are  supported  by 
retaining  walls  of  masonry.  The  outer  slope  of  the  dam  may 
vary  between  i  on  ij  and  i  on  3^,  according  to  the  character 
of  the  material.  Light  sand  requires  the  flattest  slope.  A  firm 
mixture  of  gravel  and  clay  will  stand  a  slope  of  about  i  on  ij. 
The  inner  slope  of  the  dam  should  be  about  J  on  i  greater  than 
the  outer  slope.  It  is  not  unusual,  as  in  the  case  of  the  Ashti 
dam  (Fig.  137),  to  make  the  inner  slope  near  the  top  a  little 
steeper  than  the  lower  portion  of  the  slope,  the  object  being  that 
a  steep  slope  from  i  on  i  to  i  J  reflects  the  waves,  while  a  flatter 
slope  breaks  them  up. 

The  top  width  of  the  dam  depends  somewhat  on  circum- 
stances. A  top  width  of  6  feet  is  the  minimum  which  should  be 
employed,  and  for  a  high  dam  is  too  small.  A  good  rule  as  to  the 
minimum  top  width  of  earthen  dams  50  feet  in  height  and  over 
is  to  make  their  breadth  10  feet.  For  dams  under  50  feet  the 
top  width  should  be  8  to  6  feet.  As  the  dam  settles  in  course  of 


FOUNDATIONS  365 

time,  its  top  should  be  built  up  by  adding  material  to  the  required 
height.  The  dam  should  always  be  several  feet  higher  than  the 
highest  flood  mark  in  order  to  prevent  waves  from  topping  it. 
Thus  the  height  of  the  dam  above  the  crest  of  the  discharge  weir 
should  be 


in  which  D  equals  the  depth  of  water  in  the  reservoir  above  the 

weir  crest  at  maximum  flood; 
X  equals  the  height  of  the  top  of  the  stone  pitching 

above  the  surface  of  the  maximum  flood; 
C  is  a  constant  equal  to  2  or  3  feet  according  to  circum- 
stances, and  is  equal  to  the  vertical  height  of  the 
top  of  the  dam  above  the  top  of  the  pitching. 

293.  Foundations.  —  The  foundation  of  an  earth  dam  should 
be  examined  with  great  care.  The  best  material  on  which  to 
found  it  is  sandy  or  gravelly  clay,  fine  sand  or  loam.  Such  a 
structure  should  never  be  built  on  shale  or  slate;  or  on  firm 
rock  unless  a  masonry  core-wall  is  used,  when  a  firm  bonding 
to  prevent  creep  of  water  can  be  obtained  between  this  and  solid 
rock  up  to  the  level  of  the  crest  of  the  dam.  A  low  concrete 
core-wall  may  be  built  on  bed-rock,  and  in  the  lowest  part  of  the 
latter  loose  rock  be  piled  on  the  up-stream  side  to  collect  seepage 
water.  This  may  then  be  led  by  a  drain-  pipe  through  the  core- 
wall  to  the  lower  toe  of  the  earth  embankment.  Great  care 
should  be  taken  in  searching  for  springs  or  quicksands  in  the 
foundation.  Sometimes  a  quicksand  may  be  discovered  at  some 
little  depth  beneath  a  hardpan  or  other  suitable  foundation.  In 
such  a  case  it  is  sometimes  possible  to  seal  over  the  quicksand 
under  the  embankment,  and  found  the  latter  on  the  upper  stratum. 
Such  an  expedient  is  not  entirely  free  from  risk,  and  great  care 
should  be  taken  in  joining  the  toe  of  the  embankment  to  the 
foundation  material,  if  necessary  spreading  earth  and  clay  over 
the  surface  of  the  valley  for  some  distance  on  either  side  of  the 
dam. 

The  first  thing  to  be  done  in  preparing  the  site  of  the  dam 
is  to  remove  all  soil  to  a  depth  equal  to  that  penetrated  by  roots. 


366  EARTH  AND    LOOSE-ROCK   DAMS 

If  firm  and  impervious,  the  soil  may  be  scored  by  longitudinal 
trenches,  which  will  give  the  proper  adhesion  between  the  founda- 
tion and  the  embankment,  and  prevent  the  slipping  of  the  latter. 
If  a  puddle  wall  or  masonry  core  is  to  be  built  into  the  dam, 
the  foundation  for  this  should  be  sunk  to  a  sufficient  depth  to 
secure  its  permanence.  If  a  homogeneous  dam  is  to  be  built 
and  the  foundation  material  exposed  is  not  impervious,  a  trench 
should  be  dug,  and  this  filled  with  some  puddle  material,  as 
clayey  gravel  or  gravelly  loam,  moistened  and  rolled  or  packed 
in  layers;  or  with  concrete  in  cement. 

294.  Foundations    of   Masonry    Core   and    Puddle    Walls.— 
The  foundations  for  a  masonry  core- wall  should   always  rest 
only  on  firm,  homogeneous  rock,  as  described  for  foundations 
of  masonry  dams  (Art.  331).     In  any  case  where  only  loose  ma- 
terial or  disintegrated  rock  is  to  be  found,  some  other  form  of 
earth  dam  than  one  having  a  masonry  core  is  to  be  recommended. 
The  core-wall  should  have  a  perfect  bond  with  the  clean  bed- 
rock, both  under  the  dam  and  up  the  sides  of  the  hill  to  a  level 
with  its  crest;  otherwise  it  may  afford  the  means  for  creep  of 
seepage  water  which  will  eventually  destroy  the  structure. 

When  a  puddle  wall  of  clay  or  earthy  gravel  is  employed 
instead  of  a  masonry  core,  equal  precautions  with  regard  to 
its  foundation  are  necessary,  though  in  the  case  of  a  puddle  wall 
it  is  not  necessary  or  desirable  to  found  it  on  rock.  The  best 
foundation  for  a  puddle  wall  is  fine,  loose  material,  as  gravel  or 
sand  containing  earthy  material;  a  firm  bed  of  clay,  or  a  close- 
grained  hardpan.  This  should  be  cleaned  off  and  trenched  so  as 
to  insure  a  firm  seat  and  close  bond  for  the  puddle  wall. 

295.  Springs  in  Foundations. — It  is  a  common  occurrence  to 
encounter  springs  in  the  excavations  for  the  foundations  of  dams 
either  of  masonry  or  of  earth.     These  springs  are  a  great  menace 
to  the  integrity  of  the  structure,  and  it  is  due  to  their  presence  that 
some  of  the  most  disastrous  failures  of  dams  have  occurred. 
Some  engineers  recommend  that  springs  be  carried  away  in  drains 
securely  puddled.     This,  however,  is  a  difficult  operation  and 
one  rarely  possible  of  accomplishment.     A  single  large  spring 
may  be  easily  followed  back  in  a  cutting  until  it  can  be  taken  up 


MASONRY  CORES  367 

in  a  pipe,  but  ordinarily  the  foundation  is  underlain  by  a  number 
of  small  springs. 

One  excellent  way  of  dealing  with  a  foundation  containing  a 
number  of  small  springs  is  to  begin  construction  from  the  inner 
toe  and  work  progressively  across  the  base  of  the  dam  to  the 
outer  toe,  in  such  manner  as  to  force  the  springs  out  from  under 
the  foundation,  or,  if  possible,  to  smother  them.  Where  a  cement 
puddle  or  core-wall  is  used,  in  the  foundation  of  which  a  number 
of  large  springs  are  encountered,  the  foundation  may  be  closed 
over  these  by  leaving  a  little  hole  or  tube  through  which  the  spring 
may  issue.  This  is  coaxed  upward  as  the  wall  is  carried  up  until 
a  point  is  reached  above  which  the  spring  does  not  rise.  Or  the 
diameter  of  the  tube  may  be  diminished  until  it  becomes  too 
narrow  for  the  passage  of  the  water  owing  to  its  diminished  head 
and  increased  friction. 

296.  Masonry  Cores,  Puddle  Walls,  and  Homogeneous  Em- 
bankments.— There  is  still  a  wide  difference  among  engineers 
as  to  the  best  type  of  earth  dams.  Occasionally  in  England 
and  in  a  few  cases  in  our  own  country  earth  dams  have  been 
built  up  homogeneously,  the  front  or  water  face  being  covered 
with  a  deep  layer  of  some  puddle  material,  as  clayey  loam.  This 
practice,  however,  is  falling  into  disuse,  and  engineers  now  rarely 
trust  to  a  puddle  face  alone  for  protection  against  leakage. 

A  wooden  or  plank  core  should  never  be  employed.  The 
material  is  sure  to  rot  and  decay,  while  the  smooth  surface  of 
the  boards  offers  an  excellent  route  along  which  leakage  water 
will  travel  until  it  finds  an  outlet.  Again,  it  is  impossible  to 
make  a  wooden  wall  sufficiently  substantial  to  withstand  leakage 
and  the  tendency  to  rupture  which  may  result  from  the  settling 
of  the  bank.  Recently  steel  core-walls  have  been  used  both  in 
earth  and  in  rock-fill  dams  in  the  West  (Arts.  307  and  311). 

The  masonry  core  is  in  great  favor  with  many  engineers, 
both  in  Europe,  India,  and  America.  A  central  core  of  puddled 
earth  is  subject  to  rupture  from  the  settlement  of  the  embank- 
ment. Both  are  practically  impervious  to  leakage,  and  the 
masonry  core  especially  so  to  burrowing  animals.  In  build- 
ing such  core  walls  they  must  be  carried  sufficiently  deep  to  reach 


368  EARTH  AND    LOOSE-ROCK   DAMS 

some  impervious  stratum,  and  far  enough  into  the  side  walls  of 
the  valley  to  prevent  the  passage  around  their  ends  of  seepage 
water  which  would  travel  along  their  impervious  faces.  The  con- 
struction of  a  dam  composed  for  a  portion  of  its  length  of  earth 
and  for  the  remainder  of  loose  rock  or  masonry  is  dangerous, 
and  the  writer  is  opposed  to  such  combinations  which  have  re- 
cently been  measurably  condemned  by  the  abandoment  of  this 
type  for  the  new  Croton  dam.  Moreover,  masonry,  either  as  a 
retaining  wall,  core,  or  culvert,  is  rigid,  while  the  other  material 
is  flexible,  and  any  settlement  in  the  latter  leads  to  rupture  in 
the  former.  Furthermore,  masonry  offers  a  smooth  surface 
for  the  travel  of  seepage  water  and  thus  tends  to  aid  any  internal 
erosive  action  which  may  set  in. 

The  earth  dam  with  masonry  core  is  probably  the  most  popu- 
lar at  present,  especially  for  very  high  dams  and  those  with  which 
other  masonry  structures  combine,  as  masonry  wasteways  or 
extensions  of  the  dam,  for  then  a  safe  bond  can  be  made  between 
the  core-wall  and  its  adjoining  masonry  work.  Magnificent 
examples  of  such  works  have  recently  been  built  for  the  Boston 
water-supply  and  the  New  York  water-supply. 

Engineers,  to  a  limited  extent  in  India  and  to  a  large  extent 
in  our  Western  irrigation  region,  favor  the  earth  dam  built  up  in 
homogeneous  layers  without  puddle  or  core-wall,  each  carefully 
rolled  or  tramped  over  in  such  a  manner  that  the  whole  dam  is 
a  dry  puddle  wall.  This  character  of  construction  has  all  the 
advantages  of  imperviousness  to  leakage  if  the  work  is  well  done, 
while  it  is  free  from  the  disadvantages  possessed  by  dams  with 
central  cores,  namely,  a  smooth  surface  along  which  water  may 
travel,  and  liability  to  rupture  in  the  wall.  With  such  a  form 
of  dam  one  or  more  trenches  are  usually  excavated  in  the  foun- 
dation and  parallel  with  its  axis.  These  may  be  carefully  packed 
with  the  material  of  which  the  dam  is  built,  or  with  puddle  mate- 
rial to  prevent  leakage  under  and  around  the  dam.  The  embank- 
ment material  as  laid  down  may  be  so  selected  as  to  get  the  finest 
and  least  pervious  constituents  in  the  front  portion  of  the  dam, 
leaving  the  heavier  and  coarser  material  to  the  rear  to  give  stability. 
Such  a  form  of  construction  is  popular  with  the  Reclamation 


MASONRY   CORE-WALLS    IN    EARTH   EMBANKMENTS     369 

Service,  and  practically  converts  the  dam  into  one  having  an 
impervious  face  of  great  thickness  (Fig.  134). 

297.  Masonry  Core-walls  in  Earth  Embankments. — The  pri- 
mary object  of  a  masonry  center  wall  is  to  afford  a  water-tight  cut- 
off to  water  of  percolation.  It  is  the  dam  proper,  for  it  retains 
the  water  in  the  reservoir,  the  earth  embankment  on  either  side 
being  only  of  service  in  keeping  the  center  wall  from  being  thrown 
down.  A  great  advantage  of  the  masonry  core  is  that  it  affords 
an  excellent  opportunity  for  making  the  connections  with  the 
outlet  tower  and  the  culverts  for  the  discharge  sluices.  These 
masonry  culverts  running  through  the  center  of  an  earth  dam 
constitute  one  of  the  weakest  points  in  its  construction,  and  offer 


FIG.  134. — Cold  Springs  Dam,  Umatilla  Project.  Oregon. 

the  greatest  opportunity  for  the  passage  of  seepage  water.  They 
can  be  so  bonded  with  the  masonry  core  as  to  form  part  of  it,  and 
preclude  the  possibility  of  the  water  following  along  the  culverts. 

The  masonry  core  should  be  carried  to  a  height  equal  to 
that  of  the  sill  of  the  escape-way,  while  in  very  high  dams  it  is 
well  to  raise  it  to  the  extreme  flood  height.  It  should  be  as 
thin  as  possible  in  order  to  reduce  its  cost,  yet,  as  some  move- 
ment may  take  place  in  the  embankment  owing  *  to  settlement, 
it  should  be  sufficiently  heavy  to  be  self-supporting.  A  safe 
and  usual  rule  is  to  give  it  a  top  width  of  4  to  5  feet,  and  to  in- 
crease its  thickness  toward  the  bottom  at  the  rate  of  about  i 
foot  in  10.  This  center  wall  should  be  composed  of  the  best 
concrete. 

An  excellent  example  of  a  masonry  core  or  center  wall  for 
an  earth  dam  is  that  in  the  Titicus  dam  of  the  Croton  water- 
24 


EARTH  AND   LOOSE-ROCK   DAMS 

shed,  New  York  (Fig.  135).  This  masonry  core  is  17  feet  thick 
at  the  base,  where  it  is  founded  on  rock,  and  retains  the  same 
dimensions  for  a  height  of  85  feet,  above  which  it  tapers  to  5  feet 
in  thickness  at  the  top,  which  is  20  feet  below  the  top  of  the  em- 
bankment. The  latter  is  30  feet  wide  on  top  with  slopes  of 
2\  to  i  with  a  -  aximum  height  of  124  feet.  The  Boston  Water- 
works Department  has  a  practice  of  backing  the  core-wall  by 


FIG.  135. — Cross-section  of  Titicus  Earth  Dam,  New  York. 

a  sort  of  buttress  on  the  up-stream  side  of  fine  selected  material 
puddled,  and  containing  clayey  matter,  the  remainder  of  the 
embankment  being  of  any  coarse  and  heavy  material,  especially 
on  the  lower  side.  The  outer  slopes  are  made  of  loose  gravel 
to  prevent  slips,  which  are  more  likely  to  occur  in  clayey  soil 
(Fig.  136).  The  core- wall  has  occasional  buttresses  of  masonry 


144^  9' 
Flood  Level,  El.  251.25   ^s6*£       El.  251.5 


&&•  ;m?^ 


FIG.  136.— Core-wall  and  Earth  Embankment,  Boston  Water- works. 

to  prevent  longitudinal  creep  of  water,  and  the  up-stream  surface 
is  well  plastered  with  cement. 

298.  Puddle  Walls  and  Faces.— The  puddle  core-wall  is  not 
considered  as  satisfactory  nor  as  efficient  as  the  masonry  wall. 
The  proper  material  for  a  puddle  is  not  always  obtainable,  while 
water  for  moistening  it  is  frequently  impossible  to  obtain  in  the 


PUDDLE   TRENCH  371 

arid  region.  It  is  difficult  to  prepare,  and  requires  careful 
manipulation  in  placing.  Where  too  much  responsibility  is 
rested  in  the  imperviousness  and  security  of  the  puddle  wall  it  is 
frequently  a  menace  to  the  structure,  as  it  is  rarely  built  with 
sufficient  care.  A  puddle  wall  should  have  a  thickness  of  8  or 
10  feet  at  the  level  of  the  water  line,  and  should  increase  in  thick- 
ness downward  to  the  surface  of  the  ground  at  the  rate  of  about 
i  foot  in  10.  Where  a  puddle  wall  is  employed,  the  material  of 
which  it  is  constructed  is  usually  clay,  or  gravel  and  clay  moist- 
ened and  puddled  in  layers  of  about  6  inches  in  thickness,  and 
permitted  to  dry  slowly.  On  either  side  of  it  selected  material 
is  usually  placed,  the  remainder  of  the  dam  downward  consisting 
of  the  poorer  and  most  available  material. 

A  puddle  face,  a  form  rarely  employed,  consists  of  a  covering 


FIG.  137.— Earth  Dam  with  Puddle  Face,  Monument  Creek,  Col. 

on  the  whole  inner  face  of  a  layer  of  puddle  8  or  10  feet  in  thick- 
ness at  the  base  and  2  or  3  feet  in  thickness  near  the  summit,  and 
on  the  whole  is  placed  a  layer  of  common  soil  on  which  the  riprap 
is  laid  (Fig.  137).  In  a  few  instances  the  puddle  face  has  been 
mixed  with  small  stones  or  furnace  cinders  as  an  obstruction  to 
the  passage  of  moles,  gophers,  or  other  vermin,  which  are  the 
greatest  menace  to  any  structure  depending  for  its  imperviousness 
on  a  puddle  wall  or  face.  One  of  the  serious  objections  to  a 
puddle  face  is  its  liability  to  slip  if  the  reservoir  is  drawn  down  so 
quickly  as  not  to  give  it  time  to  dry,  for  this  is  a  slow  process  in  so 
close-grained  a  material  as  a  puddle  of  clay. 

299.  Puddle    Trench. — This    is    employed    only    where    the 
dam  is  built  up  in  homogeneous  layers  without  a  central  wall. 


372  EARTH  AND   LOOSE-ROCK   DAMS 

It  consists  of  one  or  more  trenches  excavated  longitudinally  the 
entire  length  of  the  dam  down  to  some  impervious  stratum,  or,  if 
none  can  be  found,  for  a  very  considerable  depth.  The  trench 
is  then  filled  either  with  puddle  material  built  up  the  same  as  is  a 
puddle  wall,  or  with  a  wall  of  masonry  built  up  as  a  core-wall, 
and  the  material  filling  this  trench  is  carried  up  several  feet  abovj 
the  surface  of  the  ground.  The  trench  should  be  carried  up  the 
slopes  of  the  surrounding  hills  till  it  terminates  at  a  level  with 
the  top  of  the  embankment,  and  its  bottom  should  be  level  in 
all  directions,  all  changes  of  level  being  made  by  means  of  ver- 
tical steps. 

An  excellent  example  of  a  puddle  trench  is  that  in  the  Ashti 
dam,  India  (Fig.  138).  This  trench  was  carried  down  to  a  hard 
bed  of  trap-rock,  and  in  some  places  to  consolidated  clay.  In 
this  a  puddle  was  laid  in  layers  4  inches  thick  which  were  reduced 
to  3  inches  by  watering  and  rolling.  This  puddle  trench  is  rect- 
angular in  cross-section,  lofeet  in  width  throughout,  and  generally 
1 6  feet  in  height  to  the  summit  of  the  material  filling  it.  The 
crest  of  the  material  filling  the  puddle  trench  was  raised  to  a 
height  of  i  foot  above  the  surface  of  the  ground  so  as  to  form  a 
water-tight  junction  with  the  earthwork  of  the  dam.  Across  the 
bed  of  the  river  along  the  center  line  of  the  dam  the  trench  was 
made  but  5  feet  in  width,  and  was  carried  down  to  bed-rock  and 
extended  100  feet  into  the  banks  of  the  river  on  either  side,  and 
was  filled  with  a  wall  of  concrete.  The  use  of  a  puddle  trench  is 
open  to  the  same  general  objections  as  a  puddle  or  core  wall,  but 
in  a  less  degree.  One  of  its  great  advantages  where  filled  with 
masonry  is  that  it  furnishes  an  excellent  bond  for  the  outlet  pipes 
and  culvert,  and  as  a  barrier  against  creep  of  water  along  these. 
A  good  example  of  this  form  of  construction  is  to  be  found  in  the 
Santa  Fe  dam  (Fig.  139),  in  the  bottom  of  which  are  four  parallel 
masonry  puddle  trenches. 

300.  Homogeneous  Earth  Embankment. — This  type  of  dam 
is  considered  by  the  writer  and  by  many  other  engineers  as  the 
most  safe,  efficient,  and  economic.  It  is  generally  preferable  in 
the  arid  region  because  of  the  saving  in  transportation  of  cement, 
rock,  or  selected  materials  for  a  core-wall.  It  should  be  of  the 


HOMOGENEOUS    EARTH   EMBANKMENTS 


373 


9 


374  EARTH   AND   LOOSE-ROCK   DAMS 

same  density  throughout,  and  composed  of  material  practically 
impervious  to  water.  It  should  form  with  the  natural  material 
on  which  it  rests  a  perfectly  homogeneous  mass.  Practically  it 
is  difficult  to  obtain  such  a  structure,  though  the  engineer  should 
come  as  near  as  possible  to  the  ideal.  In  a  homogeneous  earth 
dam  the  up-stream  face  is  that  point  at  which  the  water  pressure 
ceases  either  by  the  water  ceasing  to  penetrate  the  body  of  the 
dam  or  by  its  having  free  egress  from  the  down-stream  side.  A 
core-wall  will,  on  the  other  hand,  stop  the  small  amount  of  water 
coming  through  a  new  dam,  and  this  will  accumulate  in  the 
earth  against  the  core,  and  will  finally  permeate  the  whole  body 
of  the  dam  above  the  wall,  thus  causing  the  water  pressure  which 
should  be  exerted  against  the  up-stream  face  to  be  exerted  against 
the  core.  The  whole  duty  of  the  dam  is  then  performed  by  the 
core-wall  and  the  material  below  it. 

If  enough  impervious  material  cannot  be  had  to  build  the 
whole  structure  up  homogeneously  in  layers,  the  up-stream  third 
or  half  should  be  built  of  the  best  material  available,  the  poorest 
and  heaviest  being  put  in  the  lower  side.  These  two  classes  of 
material  should  be  well  worked  into  one  another  so  as  to  give 
a  perfect  bonding.  This  practically  converts  the  principal  third 
of  the  dam  into  a  dry  puddle  face,  only  the  whole  structure  is 
built  up  at  the  same  time  in  irregular  layers  of  6  to  15  inches 
in  thickness,  and  well  tramped  over  or  dry-puddled.  By  not 
building  it  in  uniform  layers  a  better  bond  is  given  to  the  struc- 
ture. With  such  a  form  of  construction  any  water  which  may 
soak  through  the  upper  third  will  find  free  egress  from  the  dam 
on  its  lower  side.  The  result  will  be  to  keep  water  out  of  the  dam 
if  possible,  but  when  it  enters  to  pass  it  through  quickly.  The 
layers  should  be  so  disposed  that  the  outer  edges  or  extremities 
of  each  shall  be  higher  than  the  center  of  the  layer  by  from  2  to 
4  feet.  As  built  in  the  West  with  teams  and  scrapers,  no  run- 
ways should  be  provided,  the  teams  being  driven  over  the  whole 
surface,  thus  adding  to  the  density  and  compactness  of  the  struc- 
ture. As  each  layer  is  built  up  it  is  well  to  drag  or  harrow  it, 
and  then  pass  a  heavy  roller  over  it.  The  same  result  can  be 
produced  by  rolling  it  with  a  heavy  roller  having  annular  pro- 


376  EARTH   AND   LOOSE-ROCK  DAMS 

jections  or  rings  on  its  surface.  Excellent  results  in  compact- 
ing such  dams  have  recently  been  gotten  on  the  Santa  Fe  dam 
(Fig.  139)  by  keeping  a  band  of  goats  tramping  constantly  back 
and  forth  over  the  surface  during  the  period  of  construction, 
loo  goats  doing  the  work  for  about  20  wheel  scrapers. 

301.  Embankment  Material. — The  ideal  material  of  which 
to  construct  an  earth  dam  is  such  a  mixture  of  gravel,  sand, 
and  clay  that  all  the  coarser  interstices  between  the  particles 
of  the  former  shall  be  filled  by  the  sand,  and  that  all  the  minute 
openings  between  the  particles  of  this  material  shall  be  filled 
by  the  still  finer  particles  of  clay.  This  would  give  such  a  com- 
position that  water  would  pass  through  it  with  the  greatest 
amount  of  resistance,  and  the  bank  would  be  practically  im- 
pervious. In  practice,  with  proper  care  to  mix  the  materials 
so  as  thoroughly  to  incorporate  them  one  with  the  other,  the 
following  proportions  should  be  used: 

Coarse  gravel i  .00  cubic  yard 

Fine  gravel 0.35     "         " 

Sand 0-15     "         " 

Clay 0.20     "         " 

Giving  a  total  of  about  1.70  cubic  yards,  which  when  well  mixed, 
compacted,  and  rolled  can  be  reduced  to  about  i\  cubic  yards 
in  bulk.  These  proportions  will  rarely  be  obtained,  but  the 
effort  should  be  to  approach  as  nearly  to  them  as  possible  in 
order  to  produce  the  best  combination  of  materials.  Weight 
is  a  valuable  property  in  an  earth  embankment,  and  such  a  com- 
bination as  above  given  possesses  the  greatest  amount  of  weight 
obtainable  with  earth.  The  sand  and  gravel  lack  cohesiveness 
but  have  stability,  while  clay,  though  cohesive,  is  liable  to  slip 
if  unsupported.  The  above  combination  possesses  the  qualities 
of  weight,  cohesiveness,  stability,  and  imperviousness,  while  the 
angle  of  repose  or  the  slope  which  can  be  given  is  about  midway 
between  that  possible  with  fine  sand  and  that  to  be  obtained  with 
shingle  or  a  mixture  of  sand  and  clay.  If  judgment  be  used  in 
choosing  materials,  dirty  gravel  or  that  possessing  a  large  amount 
of  soil  and  sandy  matter  may  often  be  found  which  will  give 
nearly  the  proportions  above  specified. 


EMBANKMENTS   OF    SAND  377 

Recent  experiments  by  Prof.  E.  W.  Hilgard  with  alkali  soils 
in  California  (Art.  44)  shows  that  black  alkali — carbonate  of 
soda — puddles  clay  soils  so  as  to  make  them  impervious  and 
untillable,  and  sandy  soils  so  as  to  produce  a  tough  hardpan 
through  which  water  cannot  pass.  Puddle  walls  in  dams  watered 
with  a  one-tenth  per  cent  solution  of  carbonate  of  soda  will  be 
rendered  water-tight,  and  so  tough  and  solid  as  to  resist  pressure 
and  erosion  to  a  remarkable  degree. 

302.  Embankments   of   Sand. — Sand   has   occasionally   been 
used  as  the  material  of  which  to  construct  embankments,  but 
generally  in  a  very  small  way.     A  very  large  dam  of  such  mate- 
rials is  that  at  Kalegh  reservoir,  India.     This  reservoir  has  an 
embankment  composed  entirely  of  sand,  abutting  on  rock  at  one 
end.     It  was  commenced  in  1880  and  completed  in  1882,  and  is, 
financially  speaking,  the  best  paying  irrigation  work  in  Central 
India,  having  cost  only  $60,000,  while  the  revenue  realized  aver- 
ages a  return  of  15.75  per  cent  per  annum. 

The  embankment  which  is  thrown  across  the  river  Bandi  is 
composed  entirely  of  sand,  the  inner  slope  four  to  one,  and  the 
outer  slope  three  to  one,  the  width  at  the  top  being  20  feet.  At 
the  point  at  which  the  embankment  abuts  on  to  the  rock  a  core- 
wall  of  masonry,  30  feet  long  and  2  feet  thick,  was  built  into  the 
dam  to  prevent  water  creeping  along  the  face  of  the  rock  and  en- 
dangering the  sand  dam.  Rubble  at  the  toe  of  the  outer  slope, 
10  feet  wide  and  3  feet  high,  prevents  any  erosion  of  the  outer 
slope.  These  measures  have  been  completely  successful.  The 
length  of  the  dam  is  730  feet  at  the  top  and  305  feet  at  the  bottom, 
and  the  height  50  feet.  The  greatest  depth  of  water  impounded 
is  30  feet,  of  which  25  feet  is  available  for  irrigation. 

The  waste-weir,  cut  out  of  the  rocky  spur  of  Kalegh  hill,  is 
only  loo  feet  long.  The  area  of  the  lake  is  1540  acres,  and  the 
total  capacity  of  the  tank  is  13,300  acre-feet. 

303.  Hydraulic-fill  Dam. — The  idea  of  building  up  a  reser- 
voir embankment  of  earth  by  washing  or  hydraulicking  earth 
from  above  it  and  sluicing  it  into  position  originated  in  the  earliest 
days  of  hydraulic  mining  in  California.     Perhaps  the  first  struc- 
ture of  this  kind  to  be  built  was  the  San  Leandro  dam,  near 


378  EARTH  AND   LOOSE-ROCK   DAMS 

Oakland,  Cal.  (Art.  304).  A  smaller  and  similar  type  of  dam 
is  that  described  as  having  been  built  on  the  Turlock  canal  (p.  141). 
More  recently  two  excellent  examples  of  such  structures  have 
been  built  which  have  been  fairly  satisfactory,  especially  as  to 
cost;  namely,  at  Tyler,  Tex.,  and  at  La  Mesa,  Cal.  The  former 
structure  is  of  but  moderate  dimensions,  being  but  32  feet  high, 
with  maximum  water  depth  of  26  feet,  and  capacity  of  1770 
acre-feet,  the  contents  of  the  embankment  being  24,000  cubic 
yards,  the  inner  slopes  of  3  on  i,  and  the  outer  of  2  on  i.  The 
building  of  this  embankment  was  carefully  watched,  and  it  was 
estimated  that  65  per  cent  of  the  material  sluiced  into  it  was 
sand  and  35  per  cent  clay,  the  average  cost  per  acre-foot  of 
storage  capacity  being  65  cents.  The  total  cost  of  the  work, 
including  outlet-pipes,  etc.,  was  but  4!  cents  per  cubic  yard. 

La  Mesa  dam  is  one  of  the  same  series  with  Sweetwater  and 
Otay,  which  provide  the  city  and  neighborhood  of  San  Diego, 
Cal.  It  is  constructed  in  a  narrow  gorge  the  materials  of  which 
are  hardpan  overlying  some  rock.  The  structure  is  66  feet 
in  height,  25  feet  in  width  on  top,  25  ij  feet  in  extreme  width 
at  the  base,  with  outer  and  inner  slopes  ij  to  i.  The  entire 
structure  was  finished  by  material  transported  by  water  and 
washed  from  the  neighboring  hillsides,  the  volume  of  the  material 
being  38,000  cubic  yards,  the  extreme  distance  of  transportation 
being  2200  feet.  The  volume  of  water  used  in  constructing  the 
dam  was  about  7  cubic  feet  per  second.  As  the  stream  of  water 
was  loaded  with  material  it  was  conveyed  by  a  24-inch  wood- 
stave  pipe  to  the  point  at  which  it  was  deposited  on  the  bank. 
In  the  first  thirty  days  21,000  cubic  yards  or  55  per  cent  of  the 
structure  was  placed,  the  ratio  of  solid  embankment  to  water 
being  3.3  per  cent.  In  the  beginning  of  the  work  a  trench  was 
excavated  in  bed-rock,  2  to  5  feet  deep  and  20  feet  wide,  through- 
out the  entire  length  of  the  center  line  of  the  structure,  and  at 
right  angles  to  this  an  outlet  culvert  was  built  through  the  dam 
consisting  of  a  concrete  conduit  48  inches  wide  by  30  inches  high, 
in  which  were  placed  two  24-inch  cast-iron  pipes.  Upon  this 
masonry  work  the  sluiced  material  was  deposited. 

304.  Combined  Earth  and  Hydraulic-fill  Dam.— One  of  the 


f 
COMBINED   EARTH  AND   HYDRAULIC-FILL   DAM 


379 


largest  and  best  types  of  such  a  structure  and  perhaps  the  first 
built  is  the  San  Leandro  dam  near  Oakland,  California.  The 
dam  is  now  500  feet  long  and  28  feet  wide.  The  original  width 
of  the  ravine  at  the  base  was  66  feet.  The  length  of  the  axis 
of  the  base  from  toe  to  toe  of  slopes  is  now  1700  feet.  The 
toe  of  the  lower  slope  is  121  feet  below  the  high-water  surface 
of  the  reservoir.  A  puddle- filled  trench  was  carried  down  30 
feet  beneath  the  original  surface,  reaching  rock,  except  at  the 


FIG.  140. — San  Leandro  Earth  and  Hydraulic-fill  Dam,  Oakland,  Cal. 

£k.    .  •«,     '-      -,          •       v.,     .. 

east  end,  where  20  to  30  feet  of  solid  clay  was  penetrated.     The 
capacity  of  the  reservoir  is  113,270  acre-feet  (Fig.  140). 

All  that  portion  of  the  dam  within  a  slope  of  i  on  2  J  at  the 
rear  and  i  on  3  at  the  face  is  built  of  choice  material,  carefully 
selected  and  put  in  with  great  care.  The  portion  outside  of  the 
i  on  2j  slope-line  at  the  down-stream  side  of  the  dam  was  sluiced 
in  from  the  adjacent  hills  regardless  of  its  character,  and  is  of 
ordinary  soil  with  more  or  less  rock.  This  process  of  sluicing 
was  to  be  carried  on  during  the  winter  months,  by  gravity  flow, 
when  there  was  an  abundance  of  water,  until  eventually  it  would 
fill  the  canyon  below  the  dam.  This  would  give  an  average 


380  EARTH  AND    LOOSE-ROCK  DAMS 

slope  of  i  on  6.7  at  the  rear.  In  the  bottom  of  the  puddle  trench 
are  three  parallel  concrete  walls  each  3  feet  wide  by  5  feet  high. 
The  wasteway  consists  of  a  tunnel  10  by  10  feet  in  section,  1487 
feet  long,  with  a  2\  per  cent  grade  and  lined  throughout  with 
masonry.  The  dam  has  a  total  volume  of  542,000  cubic  yards, 
of  which  160,000  cubic  yards  were  sluiced  in. 

305.  Interior  Slope  and  Paving.  —  The  interior  slope  of  an 
earth  dam  is  rarely  made  uniform,  while  the  exterior  slope,  though 
usually  uniform,  is  sometimes  broken  by  a  level  bench  (Fig.  136), 
the  object  of  which  is  to  prevent  serious  effect  from  the  sliding 
of  the  embankment.  This  bench  is  usually  made  from  4  to  6 
feet  in  width.  On  the  interior  slope  one  or  more  similar  benches 
are  sometimes  introduced.  In  the  case  of  the  great  dam  built 
by  the  Reclamation  Service  near  Belle  Fourche,  S.  D.  (Fig.  141), 
the  slope  is  broken  by  two  benches,  each  8  feet  in  width.  In  addi- 
tion to  this  break  in  the  slope,  it  is  not  uncommon  to  give  a  lighter 
slope  below  the  bench  and  a  steeper  inclination  for  the  last  5  to  7 
feet  at  the  top  of  the  inner  slope  (Fig.  137).  This  steepness  at 
the  top  prevents  waves  at  flood  height  from  slopping  over  the  crest 
of  the  embankment,  the  sharp  angle  breaking  the  waves  up  and 
reflecting  them  back.  The  bottom  of  the  inner  slope  is  some- 
times made  steeper  if  the  material  will  stand  it,  as  it  is  not  exposed 
to  the  air  by  the  drawing  off  of  the  water  as  is  the  upper  portion 
of  the  embankment. 

This  interior  slope  is  invariably  paved  with  cobblestones  or 
dry  rubble  tightly  driven  home  and  carefully  placed  (Fig.  137) 
or  with  concrete  blocks.  The  object  of  this  pitching  is  to  protect 
the  embankment  against  the  erosive  action  of  the  waves,  and  its 
thickness  depends  on  the  height  and  violence  of  these.  The 
maximum  height  of  the  waves  depends  on  the  fetch  or  distance 
from  the  shore  where  their  formation  commences,  and  may  be 
determined  by  Stephenson's  formula, 


where  X  equals  the  height  of  wave  in  feet  and  F  equals  the  fetch 
in  nautical  miles.  Rankine  states  that  where  an  embankment  of 
loose  stone  is  exposed  to  the  action  of  the  waves  it  should  be 


INTERIOR  SLOPE  AND  PAVING 


faced  with  blocks  set  by  hand, 
the  least  dimension  of  any  block 
in  the  facing  being  not  less  than 
two-thirds  the  greatest  wave 
height.  The  best  way  in  which 
to  lay  the  riprap  is  to  place  the 
stones  with  broad  ends  down- 
wards, rough  squared  stones 
being  preferable,  in  order  that 
they  shall  fit  fairly  close  one  to 
the  other.  The  interstices 
should  be  packed  with  small 
stone  chippings  and  finished  off 
with  earth  (Fig.  133).  This 
paving  should  be  laid  on  a 
foundation  of  10  to  20  inches  of 
small  stones  and  gravel  tightly 
compacted.  The  Belle  Fourche 
dam  is  paved  with  concrete 
blocks  8  inches  thick  and  about 
5  by  7  feet  in  plan,  laid  on  24 
inches  of  gravel  (Fig.  141). 

The  entire  height  of  the 
inner  slope  need  not  be  pro- 
tected by  a  stone  pitching. 
That  portion  of  the  slope  which 
is  below  the  level  of  the  outlet- 
sluices  requires  no  pitching  at 
all,  as  it  will  not  be  subjected 
to  wave  action.  The  lower 
portion  of  the  exposed  slope 
need  be  pitched  with  a  lesser 
thickness  than  the  upper  por- 
tion, as  the  fetch  will  be  less, 
and  consequently  the  wave 
height  less  and  its  erosive  action 
proportionately  diminished.  At 


382  EARTH  AND   LOOSE-ROCK  DAMS 

the  upper  portion  of  the  slope  the  pitching  should  be  carried 
quite  to  the  top  of  the  embankment,  and  for  safety  might  be 
carried  across  the  top  or  be  topped  by  a  parapet,  in  order 
that  any  spray  falling  on  the  top  of  the  embankment  should 
do  the  least  possible  amount  of  damage.  The  top  of  the  em- 
bankment may  be  given  a  slight  inclination  toward  the  reservoir, 
so  that  it  will  drain  into  it  and  not  outward  over  the  unprotected 
lower  slope.  For  better  protection  of  this  exterior  slope  it  should 
be  planted  with  grass,  or,  better  still,  sods  of  considerable  size 
should  be  placed  upon  it  a  few  feet  apart,  in  order  that  the  roots 
of  these  may  spread  and  entirely  protect  it  from  the  erosive  action 
of  rain  and  spray. 

306.  Earth    Embankment   with    Masonry    Retaining-wall.— 


r^^&S     ^ \    '^^^^fev^O  j 


A  B 

FIG.  142. — Cross-section  of  Kabra  Dam  (A)  and  Ekruk  Dam  (B),  India. 

It  is  sometimes  necessary  to  economize  reservoir  space,  in  which 
case  one  side  of  the  embankment  may  be  faced  with  masonry, 
though  this  combination  is  rarely  successful  or  advisable.  It 
has  all  the  disadvantages  of  both  earth  and  masonry  dams  with- 
out any  additional  advantages.  The  Kabra  embankment  in 
India  (Fig.  142,  A)  is  an  example  of  this  class  of  structure.  It 
consists  of  a  masonry  wall  on  the  front  face  of  an  earth  embank- 
ment and  having  a  steep  batter  of  about  12  on  i,  while  the  outer 
portion  of  the  embankment  and  the  lower  slope  have  the  natural 
slope  of  the  earth,  which  is  merely  used  to  give  stability  to  the 
masonry  facing  wall,  the  latter  being  the  dam  proper. 

The  masonry  may  be  put  in  as  in  the  case  of  the  Ekruk  tank 
in  India  (Fig.  142,$).     This  consists  of  a  masonry  core  of  such 


EARTH   AND   LOOSE- ROCK   DAMS  383 

dimensions  as  practically  to  form  the  entire  dam,  the  earth  being 
merely  added  to  the  bottom  of  the  slopes  to  give  stability.  In 
this  case  the  masonry  dam  has  an  inner  slope  of  12  on  i,  an 
outer  slope  of  2  on  i,  and  a  total  height  of  72  feet.  Against 
it,  on  its  upper  side,  is  an  earth  embankment  with  a  slope  of  i 
on  3,  reaching  to  about  25  feet  in  height,  and  on  the  outer  slope 
another  earth  embankment  with  a  slope  of  i  on  2,  reaching  to 
about  35  feet  in  height.  Above  this  the  masonry  is  unsupported. 

307.  Earth  and  Loose-rock  Dams — Pecos  Dams. — The  dam 
at  the  head  of  the  Pecos  Irrigation  Company's  canal,  at 
Avalon,  New  Mexico,  furnishes  an  excellent  example  of  this 
combined  construction.  This  dam  is  shaped  in  plan  like  the 
letter  L,  the  re-entering  angle  of  which  points  up-stream.  The 
long  arm  which  composes  the  main  dam  is  1025  feet  in  length 
and  varies  from  5  to  50  feet  in  height;  the  short  arm  consists 
of  a  simple  earth  embankment  530  feet  in  length,  with  an  aver- 
age height  of  8  feet.  Adjacent  to  the  end  of  the  dam  farthest 
from  the  headgate  is  a  wasteway  250  feet  wide,  excavated  in 
limestone  rock,  its  bed  being  5  feet  below  the  crest  of  the  dam. 
At  the  lower  end  of  the  rock  cut  on  the  left  bank  of  the  river  is  an 
additional  wasteway  just  below  the  end  of  the  dam.  This  waste- 
way  has  a  total  length  of  206  feet,  its  sill  being  about  2  feet  lower 
than  the  one  first  mentioned.  The  main  dam  (Fig.  143)  is  com- 
posed of  a  prism  of  loose  rock  12  feet  wide  on  top,  100  feet  wide 
at  bottom,  with  a  lower  or  outer  slope  of  i  on  ij  and  an  inner 
slope  of  i  on  {.  The  up-stream  face  is  backed  with  an  earth 
embankment  the  width  of  which  is  10  feet  at  top  and  200  feet 
at  the  bottom;  its  up-stream  slope  being  i  on  3^  and  paved  with 
12  inches  of  stone  riprapping.  The  lower  portion  of  this  slope 
near  the  outlet  sluice  is  replaced  by  10  feet  in  depth  of  loose  rock 
for  a  total  width  through  the  dam  of  75  feet,  to  prevent  under- 
cutting by  currents.  In  August,  1893,  the  dam  was  breached 
for  300  feet  in  length  and  to  its  full  height.  This  was  repaired, 
the  crest  raised  5  feet,  and  additional  spillway  provided  to  dis- 
charge 33,000  second-feet. 

In  October,  1904,  a  flood  carried  away  a  large  portion  of  the 
main  dam.  In  1905  the  Reclamation  Service  acquired  the 


3^4 


EARTH   AND    LOOSE-ROCK   DAMS 


properties  of  the  Pecos  Irrigation  Company  and  rebuilt  the  dam 
to  the  original  height  of  50  feet  on  lines  similar  to  those  of  the  old 
work.  The  spillways  were  considerably  enlarged  in  capacity 
and  the  canal,  which  heads  at  the  east  abutment  of  the  dam,  has 
its  water  surface  24  feet  below  the  dam  crest.  For  the  entire 
length  of  the  dam,  including  the  old  portion  which  remained 


FIG.  143. — Cross-section  of  Pecos  Dam. 

standing,  a  core-wall  is  placed  in  the  earth  portion,  founded  on 
bed-rock  and  reaching  to  the  level  of  water  in  the  canal  (Fig. 
144).  This  core  is  partly  of  concrete  and  partly  of  heavy  steel 
interlocking  channel  barsheet  piling;  the  latter  only  in  a  portion 
of  the  old  dam  where  it  is  driven  from  above  to  bed-rock.  From 
the  top  of  the  concrete  wall  to  the  crest  of  the  dam  is  a  reinforced 
concrete  diaphragm  12  inches  at  bottom,  8  inches  at  top,  and  24 
feet  high. 

Higher  up  on  the  Pecos  River  is  Lake  McMillan,  closed  by 


largest  obtainable  rock 
to  be  placed  along 
this  edge 


FIG.  144. — Avalon  Dam,  Carlsbad  Project,  Pecos  River,  N:  M. 

a  dam  of  similar  design,  but  larger.  This  is  1686  feet  long,  52 
feet  in  maximum  height,  and  20  feet  wide  on  top,  the  width  at 
base  being  40x5  feet.  The  up-stream  or  rock-fill  is  14  feet  wide 
on  top,  with  upper  slope  of  i  on  ij  and  lower  slope  of  i  on  J, 
backed  by  an  earth  fill  having  a  top  width  of  6  feet  and  an  outer 
or  lower  slope  of  i  on  3  J. 


MINIDOKA   PROJECT  AND    DAM,    IDAHO 

308.  Minidoka    Project    and  Dam,   Idaho. — On    the    Snake 
River,  Idaho,  near  Minidoka,  a  diversion  dam  and  main  canal 


FIG.  145. — Dam,  Regulator,  and  Head  works,  Minidoka  Project,  Idaho. 

built  by  the  Reclamation  Service  controls  nearly  150,000  acres. 
Connected  with  this  project  is  a  pumping  plant  which  will  de- 
25 


386 


EARTH  AND   LOOSE-ROCK   DAMS 


velop  17,500  horse-power  during  low  stages  of  the  river,  and  will 
thus  raise  sufficient  water  to  irrigate  76,000  acres  which  are  too 
high  to  be  supplied  through  the  gravity  system. 

The  diversion  dam  raises  the  water  47  feet  at  flood  level 
and  backs  it  up  the  river  a  distance  of  about  35  miles.  It  is 
constructed  in  two  sections  and  of  two  types:  (i)  a  rock-fill  and 
gravel  back-fill  diversion  dam,  and  (2)  a  masonry  spillway. 
The  rock-fill  dam  has  down-stream  slopes  of  ij  to  i, 
faced  on  the  up-stream  side  with  a  filling  of  gravel  having 
a  slope  of  3  to  i  (Fig.  146).  This  dam  rises  to  a  height 
of  8  feet  above  extreme  high  water,  and  is  25  feet  in  width 
on  top.  Longitudinally  through  the  center  of  the  rock-fill  dam 


ROCK  AND  EARTH  DAM 


0          20          40          60         80         100 
SCALE  OF  FEET 


FIG.  146. — Rock-Fill  Dam,  Snake  River,  Minidoka  Project,  Idaho. 

is  a  masonry  core-wall,  12  feet  in  height  and  4  feet  wide  on 
top.  The  top  of  the  dam  is  56  feet  above  low  water  and  has  a 
maximum  height  above  bed-rock  of  86  feet.  The  spillway 
consists  of  a  masonry  weir,  well  bonded  with  the  masonry  core- 
wall  of  the  rock-fill  dam,  and  having  a  maximum  breadth  of 
base  of  about  13  feet  and  a  maximum  height  of  14  feet,  the  top 
of  the  spillway  being  at  an  elevation  lofeet  below  that  of  the  crest 
of  the  dam,  and  over  it  water  is  expected  to  pass  in  maximum 
flood  to  a  depth  of  4  feet. 

At  the  end  of  the  dam  nearest  the  deepest  channel  of  the 
river  is  a  diverting-channel  (Fig.  145)  dosed  by  five  regulating- 
gates  each  8  feet  wide  by  10  feet  high  and  working  between 


LOOSE-ROCK    DAMS 


3«7 


masonry  piers  reinforced  with  concrete.  Each  gate  is  raised 
by  a  pair  of  screws  actuated  by  worm-wheel  gearing.  The  total 
height  of  the  top  of  the  regulating-bridge  above  the  bottom  of  the 
gates  is  58  feet.  The  main  south-side  canal  is  14  miles  in  length 
and  irrigates  by  gravity  8000  acres,  and  conducts  water  to  the 
pumping-station.  Its  capacity  is  850  second-feet,  and  the  capa- 
city of  the  main  north-side  canal  is  1000  second-feet.  The 
grade  in  this  canal  is 
about  0.007,  ancl  i*s 
length  12  miles.  Its  bed 
width  is  about  90  feet, 
and  the  banks  are  paved 
and  have  slopes  of  i  to  i. 
The  top  width  of  bank 
is  25  feet,  of  which  the 
outer  half  is  composed  of 
loose  rock.  The  regu- 
lating-gates at  the  head 
of  this  canal  are  14  in 
number,  separated  by 
piers  of  reinforced  concrete. 
Each  gate  consists  of  two 
leaves  5  feet  wide  by  about 
5  feet  high,  of  steel  well 

braced  and  worked  by  screw  gearing  through  hand-wheels  from 
an  over-head  bridge. 

309.  Loose-rock  Dams. — When  properly  constructed  and 
well  founded  there  is  no  apparent  reason  why  a  loose-rock  dam 
should  not  be  nearly  as  substantial  as  one  of  masonry.  Such 
dams  should  be  founded  only  on  solid  rock,  hard-pan,  or  on  very 
stiff  clay  or  other  unwashable  material.  This  type  of  dam  is 
the  outcome  of  Western  engineering  practice,  and  was  first  in- 
troduced for  the  purpose  of  storing  water  for  placer  mining. 
It  consists  of  a  mass  of  loose  rock  placed  together  with  some 
degree  of  care,  the  smaller  stones  being  used  to  fill  the  inter- 
stices between  the  larger  ones  so  that  the  settlement  shall  be 
the  least  possible.  Such  slopes  are  given  the  mass  as  it  can  safely 


Height  14  Feet 


15  Ft. 


FIG.  147. — Concreted  Waste  Weir,  Snake 
River,  Minidoka  Project,  Idaho. 


388  EARTH   AND   LOOSE-ROCK  DAMS 

stand,  and  it  is  rendered  impervious  to  water  by  a  heavy  sheath- 
ing of  tarred  planking,  an  earth  embankment  on  its  upper  face,  or 
by  a  vertical  diaphragm  of  steel  or  reinforced  concrete.  Water 
should  not  be  permitted  to  flow  over  the  crest  or  back  of  such  a 
structure,  as  it  is  liable  to  cause  settlement  which  may  result  in  its 
rupture. 

An  earth  dam  is  cheaper  than  a  rock-filled  dam  where  ma- 
terials for  such  construction  are  available.  If  transportation  is 
not  expensive  a  masonry  dam  is  frequently  cheaper  than  a  rock- 
filled  dam  owing  to  the  difference  in  cross-section  and  the  cor- 
respondingly small  amount  of  material  required  in  the  former, 
though  the  cost  per  cubic  yard  is  relatively  high.  One  of  the 
great  advantages  of  the  rock-filled  dam  is  that  it  may  be  con- 
structed with  very  little  difficulty  in  flowing  water;  another 
advantage  is  that  a  leak  is  not  the  menace  it  is  in  an  earth  or 
masonry  dam,  since  the  whole  structure  is  expected  to  leak. 
A  masonry  dam  is  at  all  times  in  a  state  of  unstable  equilib- 
rium, while  a  rock-filled  dam  tends  to  improve  with  time,  and 
if  properly  built  may  be  benefited  by  occurrences  which  threaten 
other  dams.  Such  a  dam  should  not  be  used  where  water  is 
valuable  unless  great  care  is  taken  in  providing  against  leak- 
age. The  foundation  for  a  loose-rock  dam  should  rest  on 
impervious  and  unwashable  material.  If  there  be  a  surface 
covering  of  loose  soil  or  gravel  it  should  either  be  removed  by 
carts,  or  if  the  current  in  the  stream  is  sufficient  it  may  be  washed 
away  as  the  dam  is  built  up. 

A  loose-rock  dam  should  be  built  up  in  layers  as  is  an  earth 
dam,  and  in  such  manner  that  the  center  of  each  layer  shall 
be  lower  than  the  outer  extremities.  The  best  cross-section 
for  such  a  dam  is  an  upper  slope  of  3  to  2  on  i  and  a  lower 
slope  of  i  on  i;  anything  less  than  this  cannot  be  considered 
secure. 

Mr.  R.  B.  Stanton,  as  a  result  of  his  experience  in  lining  a 
composite  dam  with  asphaltum  concrete,  recommends  that  the 
site  be  cleaned  down  to  bed-rock  and  levelled  off  with  proper 
toe  catches,  and  that  on  this  a  loose-rock  gravity  dam  be  built 
from  material  carefully  dumped  in  place  by  cableways.  The 


WALNUT    GROVE   DAM  389 

largest  stones  up  to  several  hundredweight  should  be  surrounded 
by  smaller  pieces  so  as  to  make  the  whole  mass  compact  and 
reduce  settlement  to  a  minimum.  The  inner  face  should  be  care- 
fully dry-laid  by  hand,  on  a  suitable  slope  from  a  thickness  of 
several  feet  at  the  bottom,  the  joints  being  well  filled  with  spalls. 
This  upper  slope,  starting  from  the  bottom,  should  be  stepped 
back  3  or  4  inches  for  every  5  or  6  feet  of  rise,  making  such  a  series 
of  steps  all  the  way  to  the  top,  and  on  this  surface  a  true  asphalt 
concrete  such  as  is  described  in  Art.  338,  6  inches  to  i  foot  in 
thickness  according  to  height,  should  be  placed.  The  advan- 
tages of  this  system  are  that  with  the  aid  of  the  steps  and  with 
well-made  materials  no  creeping  of  the  asphalt  surface  will  occur, 
and  a  perfect  joint  will  be  made  between  the  bed-rock,  side  walls, 
and  dam. 

310.  Walnut  Grove  Dam. — This  is  an  example  of  the  earlier 
type  of  rock-filled  dam.  It  was  destroyed  in  February,  1890,  by 
a  great  flood,  though  its  destruction  was  not  a  result  of  faulty 
design,  but  of  carelessness  in  one  or  two  details  of  its  construc- 
tion— notably  in  the  failure  to  provide  an  ample  wasteway  and 
in  the  careless  manner  in  which  the  stores  were  dumped  in  the 
center  of  the  structure.  This  darn  (Fig.  148)  rested  on  the  firm 
rock  of  the  stream  bed  throughout  its  length,  with  the  exception 
of  a  small  portion  of  the  upper  wall,  which  is  believed  to  have 
rested  on  from  5  to  12  feet  in  depth  of  loose  earth  and  gravel. 
This  was  the  weak  point  of  its  construction.  The  slopes  were 
steeper  than  the  angle  of  repose  of  the  loose  rock,  which  was 
only  held  in  position  by  the  enclosing  hand-laid  dry  walls. 

The  dam  was  420  feet  long  on  top,  138  feet  wide  at  the  bottom, 
10  feet  in  width  on  top,  and  no  feet  in  greatest  height,  and  con- 
tained nearly  50,000  cubic  feet  of  material.  It  consisted  of  a 
front  and  back  wall,  each  14  feet  thick  at  the  base  and  4  feet 
on  top,  with  a  loose-rock  filling  between;  the  whole  made  water- 
tight by  a  wooden  sheathing.  The  upper  slope  of  the  dam  was 
2\  on  i  and  the  lower  slope  ij  on  i.  This  latter,  however,  was 
increased  for  the  lower  half  of  the  dam  to  about  i  on  i  by  the 
addition  of  a  pile  of  loose  rock  after  the  completion  of  the  struc- 
ture. The  wooden  sheathing  consisted  of  logs  from  8  to  10 


390 


EARTH   AND  LOOSE-ROCK  DAMS 


inches  in  diameter  and  from  6  to  12  feet  in  length,  built  into 
the  wall  on  its  upper  face  and  projecting  therefrom  about  i  foot. 
The  upper  and  lower  faces  consisted  of  rough  blocks  of  granite 
dry-laid  in  such  manner  as  to  form  two  loose-rock  retaining-walls, 
between  which  the  body  of  the  loose  stone  was  dumped.  Verti- 
cal stringers  about  8  by  10  inches  were  bolted  to  the  projecting 


400FI 


FIG.  148. — Elevation  and  Cross-section  of  Walnut  Grove  Dam. 

ends  of  the  logs  built  into  the  upper  face,  and  these  stringers 
were  placed  about  4  feet  apart.  Upon  the  face  of  the  dam  and 
over  these  stringers  two  thicknesses  of  3  X  8-inch  planking  were 
spiked,  and  tarred  paper  was  laid  between  the  two.  The  outer 
face  of  this  sheathing  was  finally  calked,  and  the  whole  covered 
with  paramne  paint. 


ROCK-FILL    STEEL-CORE   DAM 


391 


311.  Rock-fill  Steel-core  Dam. — One  of  the  first  and  by 
far  the  largest  and  best  type  of  this  variety  of  loose-rock  dam 
is  the  Lower  Otay  dam  in  California.  The  site  chosen  is  ideal 
for  a  masonry  structure,  but  because  of  high  freights  and  in- 
accessibility it  was  decided  to  adopt  the  loose-rock  type  after 
the  masonry  foundations  had  been  laid  with  a  thickness  of  65 
feet  at  the  base  and  for  a  depth  of  40  feet.  The  plan  of  making 
a  rock-fill  dam  water-tight  by  inserting  in  its  center  a  steel 
web  plate  filling  the  entire  cross-section  of  the  canyon  originated 
with  the  president  of  the  company,  Mr.  E.  S.  Babcock.  This 
web  plate  is  held  in  position  by  a  heavy  T  iron  anchored  in  the 
top  of  the  finished  masonry  foundation  by  a  one-inch  bolt.  To 


125'  H.W 


—-882' 

CROSS-SECTION  OF  DAM 


FIG.  149.— Rock-filled  Steel-core  Dam,  Lower  Otay,  Cal. 

the  vertical  leg  of  this  the  bottom  of  the  web  plates  were  riveted 
(Fig  149).  Each  of  these  was  5  ft.  wide  and  17.5  ft.  long,  the 
bottom  plates  being  .33  inch  thick.  At  heights  between  28  and 
50  feet  the  thickness  of  the  plates  is  reduced  to  J  inch,  while 
the  plates  are  8  feet  wide  and  20  feet  with  diminishing  thickness 
above  50  feet  in  height.  The  riveted  plates  were  calked  on  the 
water  side  and  coated  with  asphalt  applied  hot  with  brushes 
To  this  a  layer  of  burlap  was  attached  while  the  asphalt  was 
still  hot,  and  this  aided  in  holding  the  asphalt  from  flowing. 
Over  this  a  harder  grade  of  asphalt  was  placed  and  the  whole 
was  encased  in  a  rubble-masonry  wall  laid  with  Portland- 
cement  concrete.  The  thickness  of  this  wall  is  6  feet  at  the  base, 
tapering  to  2  feet,  at  a  height  of  8  feet,  above  whicb  the  latter 


3Q2  EARTH  AND  LOOSE-ROCK    DAMS 

dimension  was  maintained.  The  steel  core  was  carried  into  the 
side  walls  of  the  canyon  in  a  foundation  trench  excavated  to 
solid  rock,  into  which  it  was  anchored  with  leaded  bolts. 
The  thickness  of  the  masonry  corewall  was  increased  at  the  sides 
to  a  maximum  of  20  feet  from  its  normal  width  of  2  feet,  the 
taper  extending  over  distances  of  20  feet. 

A  peculiarity  of  this  loose-rock  dam  is  that  no  portion  of  it 
was  hand-laid,  the  whole  consisting  of  a  rock-filled  embankment 
which  was  left  lying  as  it  was  dumped.  The  top  width  is  12  feet 
and  the  slopes  on  both  sides  stand  at  about  i  to  i.  The  dam 
is  565  feet  long  on  top  and  150  feet  in  height  above  bottom  of 
foundation,  the  greatest  depth  of  water  being  125  feet  with  a 
gross  storage  capacity  of  42,000  acre-feet  (PL  XXIII).  A  few 
hundred  feet  beyond  the  east  end  of  the  dam  is  a  channel  30 
feet  wide,  300  feet  long,  arid  extending  to  a  depth  of  10  feet  below 
the  crest  of  the  dam,  which  affords  ample  spillway.  There  were 
approximately  180,000  cubic  yards  of  stone  used  in  this  structure, 
which  was  quarried  below  the  dam  and  transported  by  a  Lidger- 
wood  cableway.  In  quarrying  material  two  blasts  of  4000  pounds 
and  8000  of  Judson  powder  were  exploded  simultaneously,  thus 
loosening  about  60,000  cubic  yards  of  material  at  one  discharge. 
An  outlet  tunnel  1150  feet  long  and  of  circular  section  is  provided 
through  a  narrow  part  of  the  enclosing  ridge  1000  feet  distant 
from  the  dam. 

At  East  Canyon  creek,  Utah,  has  been  built  a  modification 
of  the  above  type  of  dam  which  forms  a  reservoir  of  5700  acre- 
feet  capacity.  This  structure  is  68  feet  high  above  the  creek- 
bed  and  100  feet  in  length  on  top.  Through  the  gravel-bed  of 
the  canyon  there  was  first  sunk  a  concrete  wall  15  feet  thick 
to  bed-rock  at  a  depth  of  30  feet,  and  in  the  center  of  this  wall 
the  steel  web  plates  were  anchored.  These  were  yVinch  thick 
for  the  lower  20  feet,  diminishing  to  -f&  for  the  upper  28  feet.  On 
the  upper  slope  the  rock  fill  has  an  inclination  of  §  to  i,  and  on 
the  lower  of  2  to  i,  the  top  width  of  the  dam  being  15  feet. 

312.  Crib  Dams. — The  general  form  of  construction  and 
several  examples  of  crib  weirs  were  described  in  Articles  172  and 
173.  Structures  of  similar  design  have  occasionally  been  built  of 


394  EARTH  AND  LOOSE-ROCK  DAMS 

sufficient  height  to  form  storage  reservoirs.  The  employment 
of  cribwork  in  a  storage  dam  is  not  recommended,  as  such  work 
is  essentially  temporary  in  character.  As  a  result  of  the  alternate 
wetting  and  drying  which  it  receives  it  is  very  liable  to  rot,  and 
the  life  of  such  a  dam  is  manifestly  shorter  than  that  of  an  earth, 
loose-rock,  or  masonry  dam. 

Several  types  of  crib  and  combined  crib  and  loose-rock  dams 
have  been  constructed  in  the  Sierras  of  California  for  the  storage 
of  water  for  hydraulic  mining.  One  of  the  most  notable  of  these 
is  the  Bowman  dam,  used  for  water  storage  by  the  North  Bloom- 
field  Mining  Company,  in  California.  This  dam  (Fig.  150)  has  a 
total  height  of  100  feet  and  uniform  slopes  on  both  faces  of  i  on  i . 
Its  lower  third  on  the  up-stream  side  consists  of  a  cribwork  of  logs 
filled  with  rock,  the  cross-section  of  which  is  i  on  i,  wrhile  the  re- 
mainder of  the  dam  consists  of  loose  rock  hand-placed  and  care- 
fully laid.  The  upper  slope  of  the  dam  is  sheathed  with  plank- 
ing, and  the  lower  slope  is  faced  with  rubble  masonry  laid  in 
cement.  Through  the  bottom  of  the  dam  is  an  outlet  culvert 
constructed  of  masonry  and  cement. 

313.  Loose-rock  Dam  with  Masonry  Retaining- walls. — The 
best  existing  example  of  this  type  of  construction  is  that  closing 
the  Castlewood  reservoir  in  Colorado.  The  area  of  the  resulting 
reservoir  is  200  acres  and  its  capacity  12,280  acre-feet.  This 
dam  (Fig.  151)  is  founded  on  a  bed  of  clay  and  bowlders  from 
7  to  30  feet  in  depth,  into  which  the  facing  wall  is  carried  for  a 
depth  of  6  to  22  feet,  and  is  composed  of  an  outer  shell  or  wall  of 
large  blocks  of  coarse  rubble  masonry,  the  thickness  of  which 
on  the  up-stream  face  is  about  6  feet  on  top  and  12  feet  at  the 
bottom.  On  the  down-stream  face  the  wall  is  from  5  to  7  feet 
in  thickness,  this  face  being  laid  in  steps  the  height  of  which 
vary  from  ij  to  2\  feet  according  to  the  dimensions  of  the  stone 
blocks  forming  them.  The  main  body  or  center  of  the  dam 
consists  of  dry-laid  rubble  enclosed  between  these  two  walls. 
The  maximum  height  of  the  dam  is  63^  feet,  the  extreme  height 
above  the  foundation  being  92  feet;  it  is  586  feet  in  length  on 
the  crest,  and  100  feet  of  this  length  is  lowered  4  feet  in  order 
to  form  a  wasteway  over  which  flood  waters  may  discharge.  The 


LOOSE-ROCK  DAM  WITH  MASONRY  RETAINING-WALLS     395 

upper  4  feet  of  this  dam  is  vertical  on  both  sides,  and  its  top  is  8 
feet  in  width  and  constructed  of  rubble  masonry  in  cement.  At 
the  west  end  of  the  dam  is  an  auxiliary  spillway  40  feet  wide,  the 
total  wasteway  capacity  being  4000  second-feet.  The  outer  slope 


CROSS  SECTION 
FIG.  150. — Plan  and  Cross-section  of  Bowman  Dam. 

of  the  remainder  of  the  dam  is  i  on  i,  while  the  inner  slope  is 
10  on  i.  A  water  cushion  200  feet  long  and  25  feet  wide  is  formed 
at  the  toe  by  a  grouted  rock  pavement  3  to  6  feet  deep. 

It  is  doubtful  if  so  steep  a  slope  as  10  on  i  for  the  upper  face  is 


EARTH  AND  LOOSE-ROCK  DAMS 


safe;  probably  5  on  i  would  be  better,  while  i  on  i  for  the  rear 
face  is  ample  to  give  stability.  A  rectangular  outlet  tower  having 
a  central  well  6  by  7.5  feet  is  built  in  the  body  of  the  dam,  reaching 
to  the  top.  In  this  are  eight  1 2-inch  outlet  pipes  placed  at  four 
successive  levels.  In  such  a  structure  as  this  great  care  should  be 
taken  to  firmly  found  it  on  solid  rock  or  on  a  deep  bed  of  hard  and 
impervious  clay,  while  the  loose-rock  center  should  be  carefully 


ELEVATION 
FIG.  151. — Elevation,  Plan,  and  Cross-section  of  Castlewood  Dam,  Colorado. 

laid  to  prevent  any  inclination  to  slide  or  thrust  outward  against 
the  confining  walls. 

314.  Failure  and  Faulty  Design  of  Earth  and  Loose-rock 
Dams. — There  have  been  many  failures  of  earth  dams,  which 
have  been  due  chiefly  to  faulty  construction  and  design,  and  not 
to  the  principle  of  employing  earth  as  a  material  for  closing 
storage  reservoirs.  It  is  an  undoubted  fact  that  where  the  con- 
ditions are  suitable,  that  is,  where  desirable  material  can  be 
obtained,  an  ample  wasteway  provided  and  proper  foundations 
procured,  earth  furnishes  under  most  circumstances  the  best 
material  from  which  to  construct  a  safe  reservoir  dam.  Such 
dams  (Art.  291)  never  fall  from  sliding  or  overturning,  but 
always  because  of  careless  and  faulty  construction  acting  through 


FAILURE  AND    FAULTY    DESIGN  397 

erosion  due  to  percolation  along  the  outlet  pipes  or  foundation, 
or  along  some  structure  within  the  dam,  or  by  erosion  from  over- 
topping. 

There  are  some  notable  instances  of  large  earth  dams  built 
on  leaky  ground  which  have  remained  intact  for  many  years. 
This  is  the  case  with  some  great  earthen  dams  built  in  California 
for  the  water-supply  of  San  Francisco  which  have  been  in  constant 
use  for  over  twenty-five  years.  The  ground  at  the  site  of  one  of 
these  was  full  of  water-bearing  gravel  beds  and  a  puddle  trench 
carried  down  98  feet  below  the  bed  of  the  valley  failed  to  meet 
an  impervious  stratum.  Accordingly  the  height  of  the  dam  was 
reduced  to  50  feet  above  the  bed  of  the  valley,  and  when  the 
reservoir  was  completed  springs  appeared  and  have  continued  to 
flow  harmlessly  for  many  years.  The  San  Leandro  dam  at 
Oakland,  California,  is  120  feet  high  above  the  valley-bed,  and 
rests  on  leaky  ground.  This  dam  is  twenty  years  old,  and  has 
leaked  more  or  less  around  both  edges,  along  the  hillsides  as  well 
as  from  the  bed  below.  The  same  is  the  case  with  a  small  old 
earth  dam  built  for  the  water-supply  of  Los  Angeles,  California, 
from  below  which  a  spring  of  water  is  constantly  issuing.  It  is 
evident  that  the  upward  pressure  beneath  these  structures  is  not 
sufficient  to  overturn  or  move  them. 

Earth  dams  are  among  the  oldest  structures  in  the  world. 
There  are  many  thousands  of  them  in  India,  Europe,  America, 
and  elsewhere,  and  in  the  former  countries  some  of  these  have 
been  in  existence  for  many  centuries  and  are  still  as  safe  and 
substantial  as  when  built;  in  fact,  they  have  improved  with  age. 

Loose-rock  dams  are  yet  to  a  certain  extent  experimental, 
and  while  many  have  been  constructed  in  the  West,  many  have 
failed.  The  causes  of  failure  are  various,  as  are  the  modes  of 
construction.  One  of  the  first  causes  of  failure  is  an  unstable 
foundation.  It  is  not  essential  to  the  integrity  of  such  a  struc- 
ture that  water  shall  not  pass  through  it.  It  is  desirable  to  have 
it  water-proof,  chiefly  that  it  may  hold  water  for  storage;  but 
if  water  passes  through  such  a  dam,  as  it  may,  the  structure 
should  be  founded  on  such  firm  and  unerodable  material,  and 
should  itself  have  such  natural  slopes,  that  the  passage  of  water 


398  EARTH   AND  LOOSE-ROCK   DAMS 

shall  cause  no  erosion  within  it  or  about  it,  and  therefore  no 
settlement.  Another  cause  of  failure  is  to  be  found  in  such  steep 
slopes  that  the  loose  rock  will  not  maintain  them  or  that  waste 
water  overtopping  the  structure  will  give  it  a  tendency  to  assume 
natural  slopes  which  will  reduce  the  height  of  the  dam  and  thus 
lead  to  its  destruction.  Unless  a  loose-rock  dam  be  given  such 
low  slopes  as  are  not  likely  to  be  changed  by  violent  water  action 
as  ample  a  wasteway  must  be  provided  as  for  an  earth  or  masonry 
dam.  Without  further  knowledge  than  is  now  possessed  as  to 
the  causes  of  failure  in  such  structures  and  their  proper  design, 
every  precaution  should  be  taken  in  their  construction  to  make 
them  as  safe  against  settlement  by  carefully  building  them  up  in 
horizontal  layers,  as  secure  against  erosive  action  of  water  through 
and  around  them,  and  as  free  from  the  danger  of  overtopping  by 
supplying  ample  wasteway,  as  is  desirable  in  the  construction  of 
an  earthen  or  a  masonry  dam. 


CHAPTER   XVII 

MASONRY    DAMS 

315.  Theory  of  Masonry  Dams. — Masonry  dams  are  employed 
both  for  diversion  and  storage  works,  and  may  be  so  constructed 
as  either  to  permit  flood  water  to  pass  over  their  crests  or  to  have 
it  passed  around  one  end.  If  the  dam  is  to  be  used  for  storage 
purpose?  only,  and  a  sufficient  wasteway  can  be  provided,  it  may 
be  designed  according  to  one  of  the  theoretical  formulas  or  from 
one  of  the  type  profiles  given  hereafter.  Dams  constructed  by 
theseformulas  contain  the  minimum  amount  of  material  necessary 
to  enable  them  to  perform  their  functions  of  holding  up  the  storage 
water,  and  are  not  sufficiently  substantial  to  withstand  the  shock 
produced  by  water  falling  over  their  crests.  Where  a  masonry 
dam  is  used  as  a  diversion  weir  or  as  an  overflow  weir,  it  is  im- 
possible to  design  it  on  any  of  the  theoretical  profiles.  The  chief 
considerations  requisite  in  its  design  are  that  the  pressure  of  the 
masonry  on  the  foundation  shall  not  pass  the  limit  which  the 
material  can  withstand,  that  its  cross-section  shall  be  more  ample 
and  substantial  than  that  which  would  be  required  by  one  of  the 
theoretical  profiles,  and  that  its  lower  face  shall  have  that  profile 
which  will  most  facilitate  the  easy  flow  of  water  over  its  surface 
without  the  shock  of  actual  fall. 

The  first  and  most  vital  rule  in  building  a  masonry  dam  is 
that  it  shall  rest  on  solid  and  practically  homogeneous  rock. 
A  masonry  dam  is  an  almost  absolutely  rigid  structure,  and  settle- 
ment in  any  portion  of  its  foundation  will  result  in  cracks  and 
ultimate  rupture  in  its  mass.  There  are  two  ways  in  which  a 
masonry  dam  may  resist  the  thrust  of  water:  first,  by  the  inertia 
or  weight  of  its  mass,  and,  second,  as  an  arch.  Its  safety  depends 
upon  compliance  with  the  conditions— 

i.  That  the  horizontal  thrust  of  the  water  must  be  held  in 

399 


400  MASONRY   DAMS 

equilibrium  by  the  resistance  of  the  masonry  to  sliding  forward 
or  overturning;  and, 

2.  That  the  pressure  sustained  by  the  masonry  or  its  founda- 
tion must  never  exceed  a  certain  safe  limit. 

The  thrust  of  the  water  may  be  resisted  by  being  transmit- 
ted to  the  abutments,  the  dam  acting  as  an  arch.  But  three 
dams  have  as  yet  been  built  which  depend  in  any  degree  for 
their  stability  on  arch  action,  and  the  laws  governing  this  action 
in  a  dam  are  as  yet  so  uncertain  that  they  cannot  be  depended 
upon  with  any  degree  of  security.  Some  attempt  at  solving  the 
rules  on  which  a  dam  is  dependent  for  its  stability  as  an  arch 
are  given  in  Articles  318  and  319.  According  to  J.  B.  Krantz, 
a  dam  which  is  curved  in  plan  with  a  radius  of  65  feet  or  less 
will  transfer  the  pressure  of  the  water  to  the  sides  of  the  valley 
whatever  the  height  of  the  structure.  This,  however,  does  not 
lessen  the  effect  of  the  weight  of  the  masonry,  so  that  whether 
the  structure  be  curved  in  plan  or  not,  its  weight  must  be  sup- 
ported in  the  same  way,  and  the  height  must  be  such  that  this 
weight  will  not  exceed  the  limit  of  pressure  permissible  on  the 
base.  In  France,  and  in  the  case  of  the  Fife  dam  nearPoona, 
India,  and  elsewhere,  reservoir  walls  have  been  reinforced  by 
means  of  masonry  counterforts.  If  the  wall  is  strong  enough  by 
itself  the  counterforts  are  a  useless  expense,  and  if  the  wall  is 
not  sufficiently  strong  they  will  not  prevent  it  from  yielding. 
The  masonry  intended  for  the  counterforts  would  always  be  better 
used  if  spread  over  the  mass  of  the  dam. 

316.  Stability  of  Gravity  Dams. — The  author  will  not  enter 
into  a  mathematical  discussion  of  the  theory  of  the  stability  of 
masonry  dams.  This  has  been  investigated  with  great  thorough- 
ness within  the  past  twenty-five  years,  and  nothing  which  could 
be  summarized  in  a  work  on  irrigation  would  add  to  the  value  of 
the  theories  now  held.  For  the  benefit  of  students  who  desire 
to  enter  into  the  mathematics  of  this  subject  a  list  of  authors 
is  appended  at  the  end  of  this  chapter.  Sufficient  of  the 
principles  of  the  subject  may  be  obtained  from  the  classic 
works  of  Delocre,  Krantz,  Rankine,  and  Molesworth;  or  those 
of  Baker,  Fanning,  Wegmann,  McMasters,  Church,  and  Mer- 


STABILITY    OF    GRAVITY    DAMS  4OI 

riman,    who    are    the   more   modern   American   writers  on   the 
subject. 

The  conditions  on  which  the  stability  of  gravity  dams  are 
calculated  are: 

1.  The  hydrostatic  principles  involved  in  the  pressure  of  a 
volume  of  liquid  on  an  immersed  surface;  the  fact  that  this  pres- 
sure is  perpendicular  to  the  surface;    and  that  for  rectangular 
surfaces  it  may  be  considered  as  a  single  force  applied  below  the 
water  surface  at  a  distance  equal  to  §  of  its  depth. 

2.  That  a  gravity  dam  may  fail:   i,  by  sliding  on  a  horizontal 
joint;    2,  by  overturning;    or  3,  by  crushing  of  the  masonry  or 
foundation. 

The  stability  of  the  dam  against  its  liability  to  destruc- 
tion, as  enumerated  in  condition  2,  Art.  307,  must  be  deter- 
mined— 

1.  When  the  reservoir  is  full;  and, 

2.  When  the  reservoir  is  empty. 

These  two  conditions  give  the  extreme  positions  of  the  lines 
of  pressure  in  a  dam.  The  first  causes  the  maximum  pressure 
in  any  horizontal  plane  to  be  at  the  down-stream  face  of  the 
wall,  and  the  second  produces  them  at  the  up-stream  face.  When 
the  reservoir  is  empty  the  wall  supports  only  its  own  weight, 
but  if  the  wall  has  a  uniform  thickness  the  pressure  per  square 
inch  will  be  about  85  pounds  if  the  height  of  the  structure  is 
85  feet.  If  the  faces  be  inclined  so  as  to  reduce  the  mean  thick- 
ness, the  pressure  on  the  base  diminishes  and  the  height  can  be 
accordingly  increased.  From  this  it  is  clearly  seen  that  it  is 
absolutely  necessary  to  widen  the  base  of  the  dam  by  inclining 
its  faces  if  the  wall  is  to  have  any  great  height ;  otherwise  it  would 
rupture  from  the  pressure  of  the  material  composing  its  own  mass. 
When  the  reservoir  is  full,  however,  the  water  contained  in  it 
bears  upon  the  up-stream  face  with  a  pressure  that  increases 
with  the  square  of  the  depth.  In  deep  reservoirs  this  pressure 
is  great,  and  exerts  its  effect  in  a  resultant  which  is  nearly  hori- 
zontal in  direction  and  carries  the  maximum  load  to  the  down- 
stream toe  of  the  wall.  For  stability  this  resultant  must  pierce 
the  base  in  front  of  this  lower  edge.  From  these  considerations 
26 


4O2 


MASONRY   DAMS 


FIG.  152. — Theoretical 
Triangular  Cross-sec- 
tion of  Dam. 


arises  the  necessity  of  giving  the  down-stream  face  a  greater 
batter  than  the  up-stream  face. 

The  tendency  of  the  water  pressure  to  produce  overturning 
or  sliding  and  the  weight  of  the  material  are  greater  for  each  suc- 
cessive layer  of  the  mass  of  the  dam  from  the  top  downwards. 
As  a  result  of  this  the  width  of  the  dam  at  the  top  might  theoreti- 
cally be  nil,  and  should  be  increased  down- 
wards in  such  a  proportion  as  to  render  the 
dam  capable  of  resisting  tendencies  to  crush- 
ing, sliding,  and  overturning.  From  theo- 
retical examinations  of  the  effects  of  these 
forces  it  has  been  found,  keeping  constantly 
in  view  the  necessity  of  making  the  batter  of 
the  down-stream  face  the  greater,  that  the 
dam  should  have  a  triangular  profile,  some- 
what similar  to  that  represented  in  Fig.  152. 
The  tendency  to  movement  in  a  dam 
under  change  of  water  pressure  is  about 
the  toe  and  not  at  the  center  of  the  base.  Hence  the  greatest 
stress  in  the  structure  from  horizontal  water  pressure  on  the 
face  will  be  parallel  to  and  near  the  back  face  of  the  dam. 
There  is  far  greater  danger  of  failure  from  shearing  or  sliding  on 
the  base  than  from  tensile  strain  in  the  upper  face  or  from  over- 
turning of  the  structure.  The  force  tending  to  produce  shearing 
or  sliding  increases  with  the  square  of  the  depth  of  the  water, 
and  in  straight  dams  where  tensile  stress  from  changes  of  tempera- 
ture may  exceed  the  strength  of  the  masonry  (Art.  3170),  this 
source  of  danger  is  a  serious  one  and  practically  limits  the  safe 
height  of  the  structure.  In  high  dams  where  the  length  near  the 
base  does  not  exceed  200  feet,  the  width  is  so  great  that  with  the 
ends  firmly  anchored  in  the  side  walls,  the  lower  portion  of  the 
dam  acts  to  a  great  degree  as  a  horizontal  beam  of  such  magnitude 
that  little  deformation  is  possible  from  water  pressure. 

317.  Stability  against  Sliding. — The  tendency  of  the  water 
pressure  to  slide  any  portion  of  the  dam  forward  on  a  given 
horizontal  plane  is  resisted  by  the  friction  due  to  the  weight  of 
the  mass  above  it.  The  dam  is  necessarily  founded  on  firm  rock, 


COEFFICIENTS    OF    FRICTION  IN  MASONRY  403 

.  the  disintegrated  and  weaker  portions  of  which  must  be  removed, 
and  as  a  result  the  base  is  usually  sufficiently  rough  to  offer  con- 
siderable resistance  to  sliding.  If  this  is  not  the  case,  steps  must 
be  cut  for  a  few  feet  in  depth  in  the  foundation  rock,  or  this  must 
be  irregularly  cut  in  such  manner  as  to  leave  trenches  in  which 
projections  of  the  dam  will  fit.  The  dam,  if  properly  constructed, 
is  safe  against  any  liability  to  slide  provided  its  profile  is  such 
that  it  will  resist  overturning;  therefore,  the  usual  computations 
entered  into  to  determine  whether  it  will  resist  sliding  are  practi- 
cally unnecessary.  If  it  be  constructed  of  rough  rubble  masonry 
without  regular  beds,  and  so  built  as  to  form  a  monolithic  mass, 
sliding  is  impossible.  It  is  well  known  that  the  force  required  to 
make  two  pieces  of  smooth  stone  slide  upon  each  other  when 
dry  or  joined  by  fresh  mortar  is  equal  to  about  .75  of  the  normal 
pressure.  Hence  sliding  would  only  be  possible  when  the  horizon- 
tal was  equal  to  f  of  the  sum  of  the  vertical  pressures.  In  none 
of  the  formulas  or  profile  types  ordinarily  employed  is  the  ratio 
of  the  thrust  to  the  pressure  beyond  .7,  while  it  more  ordinarily 
ranges  between  .3  and  .5. 

318.  Coefficient  of  Friction  in  Masonry. — In  the  following 
table  are  given  the  coefficients  of  friction  in  dry  masonry  of 
various  kinds. 

TABLE  XXIV. 

COEFFICIENTS    OF    FRICTION    IN    MASONRY. 

Coefficient. 

Point-dressed  granite  on  like  granite 70 

Point-dressed  granite  on  brick 63 

Point-dressed  granite  on  smooth  concrete 62 

Fine-cut  granite  on  like  granite 60 

Fine-cut  granite  on  beton  block 60 

Dressed  granite  on  granite  with  fresh  mortar 50 

Beton  blocks  on  beton  blocks 65 

Common  brick  on  common  brick 65 

Common  brick  on  common  brick  with  wet  mortar 50 

Common  brick  on  dressed  limestone 60 

Dressed  hard  limestone  on  limestone 65 

Dressed  soft  limestone  on  like  limestone 75 

According  to  J.  T.  Fanning,  let 

S  =the  symbol  of  friction  of  stability; 


404  MASONRY   DAMS 

#=the  horizontal  water  pressure  resultant; 

c  =the  coefficient  of  friction  of  the  given  section; 

w  =  the  weight  of  masonry  above  that  section; 

e  =the  vertical  downward  water  pressure  resultant; 

z  =the  maximum  upward  water  pressure  resultant; 

d  —  the  ratio  of  effective  upward  water  pressure  to  the  maximu  m. 
Then,  when  S  and  x  are  equal  to  each  other,  the  wall  is  on  the 
point  of  motion  and  S  must  be  increased.  This  has  to  be  done 
by  adding  more  weight  to  the  wall.  This  weight  should  be 
increased  until  it  is  able  to  resist  a  thrust  of  at  least  1.5^,  when 

S  =  (w  +  e—cfz)  Xc  =  i.$x. 

The  wall  has  a  small  margin  of  fractional  stability  when  x  = 
2.2$  tons.  Ordinarily  the  weight  or  pressure  of  the  wall  far 
exceeds  this  figure,  and  is  usually  from  5  to  12  tons  per  square 
foot.  For  equilibrium,  let 

X  <  CW  -f  W/, 

in  which  m  is  the  cohesion  of  the  masonry  per  square  unit  and 
/  the  length  of  the  joint  at  the  section  above  x.  The  value  of 
m  is  so  considerable  that  ml  may  be  considered  as  a  margin  of 
safety,  when  we  have  x  =  cw.  To  find  what  value  of  c  will  pre- 

x 
vent  sliding,  we  have  c  =  — . 

w 

A  masonry  wall  must  be  founded  upon  solid  rock  which  is 
either  naturally  uneven  or  must  be  made  so,  and  it  must  be  made 
of  rubble  masonry  or  concrete  not  laid  in  courses.  As  there 
can  therefore  be  no  smooth  planes  to  slide  one  upon  the  other, 
the  coefficient  of  friction  in  the  mass  must  be  many  times  the 
superincumbent  weight;  and  we  may  conclude,  therefore,  that 
there  is  no  possible  danger  of  failure  from  sliding. 

319.  Stability  against  Crushing.— According  to  the  method 
given  by  Debauve,  when  the  reservoir  is  full  and  the  resultant 
of  the  pressure  of  the  water  and  the  weight  of  the  masonry  inter- 
sects the  base  at  one-third  of  its  width  from  the  down-stream 
toe,  the  maximum  pressure  is  at  this  toe,  and  is  double  what 
the  pressure  per  square  inch  would  be  if  the  weight  were  uniformlv 
distributed  over  the  whole  base.  When  the  reservoir  is  empty 


STABILITY    AGAINST    CRUSHING  405 

the  conditions  are  reversed,  the  maximum  pressure  being  at  the 
up-stream  toe  and  equal  to  double  the  average  pressure  on  the 
base. 

From  this  proposition  Mr.  James  B.  Francis  differs.  He 
believes  that  the  pressures  near  the  base  of  the  wall  are  prac- 
tically zero,  and  that  these  pressures  are  transferred  to  the  cen- 
tral part  of  the  mass,  where  the  resistance  to  crushing  is  greatest. 
In  other  words,  that  the  masonry  is  not  perfectly  rigid,  and  that 
it  becomes  accordingly  unnecessary  to  take  account  of  crushing 
pressures  in  a  dam  less  than  200  feet  in  height.  In  this  opinion 
other  authorities  agree  with  Francis  to  a  limited  extent,  though 
all  prefer  to  calculate  the  limit  of  pressure  in  the  usual  manner, 
namely,  to  measure  the  pressures  near  the  face  of  the  wall,  as 
that  gives  a  safer  factor,  though  it  may  be  unnecessarily  high. 
As  parts  of  the  dam  are  built  at  different  times  in  the  year  and 
under  different  conditions,  the  structure  cannot  be  truly  homo- 
geneous. The  absence  of  fractures  at  the  thin  portion  near  the 
toe  of  most  dams  indicates  the  absence  of  excessive  strains  at  that 
point;  it  is  therefore  more  probable  that  the  real  point  of  dis- 
tribution of  pressure  lies  somewhere  between  the  extremes  enu- 
merated by  Debauve  and  Francis.  Up  to  the  limit  of  200  feet 
in  height  there  is  no  doubt  that  the  crushing  strength  of  well- 
laid  masonry  need  not  be  considered. 

The  following,  from  Wegmann,  is  a  brief  synopsis  of  a  simple 
formula  for  finding  the  distribution  of  pressure  at  any  point  in 
a  dam: 

Let  W  =  the  total  pressure  on  the  base; 

u  =the  distance  of  W  from  the  nearest  edge; 

p  =the  maximum  pressure  on  the  foundation; 

q  =the  minimum  pressure  on  the  foundation; 

/   =the  length  of  the  joint  or  base  under  consideration. 

2W  f  T>U  \  I 

Then  p  =  ~7~\2  —  V  J-     When   u  =  -,  or  in  other  words  the 

o 

2W 

pressure  is  within  the  middle  third  of  the  base,  p  =  —r~.  If 
the  pressure  is  without  the  middle  third  there  will  be  tension  in 


406  MASONRY   DAMS 

the  mass.  As  it  is  unsafe  to  depend  on  the  tension  in  masonry,  it 
would  be  best  to  neglect  this  in  calculating  the  pressure  on  the 

2\¥ 

foundation,    and    this    will    become    p  = .       Another    simple 

3u 

formula  for  determining  the  pressure  on  the  base,  and  one  which 
leads  to  practically  similar  results,  is  the  following,  given  by 
Ira  O.  Baker: 

W     6Wu 
f="~l J~ 

320.  Limiting  Pressures. — The  limiting  pressures   which  it 
may  be  safe  to  permit  in  masonry  differ  considerably  accord- 
ing to  various  authorities.     From  actual  tests  these  pressures 
differ  according  to  the  dimensions  of  the  masonry  blocks,  and 
it  is  probable  that  much  greater  pressures  can  be  sustained  per 
unit  of  area  in  the  interior  of  large  masses  than  in  the  smaller 
experimental  blocks  or  near  the  surface  of  the  mass.     The  fol- 
lowing pressures  are  ordinarily  accepted:     Brick,   120  pounds; 
sandstone,   130  pounds;    limestone,   152  pounds;    granite,   155 
pounds  per  square  inch.     It  is  not  advisable  to  allow  either  a 
direct  or  resultant  pressure  exceeding  140  pounds  per  square 
inch  within  i  foot  of  the  face  of  rubble  masonry  or  exceeding 
200  pounds  per  square  inch  in  the  heart  of  the  work.     On  some 
of  the  great  structures  already  built  limits  of  pressure  as  low  as 
85  pounds  have  been  adhered  to,  while  pressures  exceeding  200 
pounds  per  square  inch  have  been  permitted  in  the  Almanza 
and  the  Gros  Bois  dams  in  Europe. 

Among  the  great  dams  which  have  been  constructed  the 
pressures  vary  between  5.8  tons  per  square  foot  in  the  Verdon 
dam  in  France  and  14.6  tons  per  square  foot  in  the  Gros  Bois 
dam,  while  the  proposed  Quaker  Bridge  dam,  in  New  York,  was 
designed  for  a  maximum  pressure  of  16.6  tons  per  square  foot. 
It  is  probable,  however,  that  a  safe  average  limit  is  that  already 
given  of  from  140  to  200  pounds  per  square  inch. 

321.  Stability  against  Overturning. — To  insure  ample  safety 
against  all  the  causes  of  failure  in  a  dam  in  addition  to  the  other 
conditions  already  fixed,  the  lines  of  pressure  must  lie  within 


STABILITY   AGAINST    OVERTURNING  407 

the  center  third  of  the  profile,  whether  the  reservoir  be  full  or 
empty.  This  last  condition  precludes  the  possibility  of  tension, 
and  insures  a  factor  of  safety  of  at  least  two  against  overturning. 
In  Fig.  1 53  suppose  the  lines  of  reaction  R  and  W  to  intersect 
the  joint  /  at  the  limit  of  its  center  third.  Taking  the  moments 
of  the  three  forces  H,  R,  and  W,  which  are  in  equilibrium  at 

about  the  point  e,  we  find  -  — ,  in  which  d=ihc  depth  of 

/  0  O 

water  at  the  joint  above  the  plane  of  /.  If  the  moments  are  taken 
about  the  front  edge  a,  the  lever  arm  of  W  will  be  double,  while 
that  of  H  remains  unchanged ;  the  factor  of  safety  against  over- 

H 


I       I/    i 


W 


FIG.  153. — Diagram  Illustrating  Wegmann's  Formula. 

turning  is  therefore  two.  It  is  equally  evident  that  if  the  line 
of  reaction  of  W  or  R  should  intersect  /  within  its  center  third,  the 
factor  of  stability  would  be  greater  than  two. 

The  following  formulas  are  taken  from  the  treatise  of  Edward 
Wegmann,  Jr.,  on  Masonry  Dams,  because  the  author  considers 
them  simple  and  accurate.  For  their  deduction  and  discussion 
the  student  should  refer  to  this  work.  The  mass  of  the  cross- 
section  of  the  dam  should  be  rectangular  and  will  contain  an 
excess  of  material  as  regards  resistance  to  the  hydrostatic  pres- 
sure of  the  water;  Pf  will  pass  through  the  center  of  the  rectangle, 
and  P  will  gradually  approach  the  front  face  eventually  reach- 
ing some  joint  x  =  a,  where  u  =  —.  The  depth  of  this  joint  below 

o 
the  top  of  the  dam  is  d  =  a\/r,  where 

P  =the  line  of  pressure,  reservoir  full; 

P'  =  the  line  of  pressure,  reservoir  empty; 


408  MASONRY  DAMS 

x  =the  unknown  length  of  the  joint; 
u  =the  distance  of  P  from  the  front  edge  of  the  joint  x; 
a   =the  top  width  of  the  dam; 
d  =the  depth  of  water  at  the  joint  x; 
r    =the  specific  gravity  of  the  masonry. 
For  the  next  course  below  the  joint  xy  where  the  dam  begins 
to  assume  a  trapezoidal  cross-section,  we  have 

?,    ....    (2) 

in  which  w  =  the  total  weight  of  masonry  resting  on  the  joint  /; 
/  =the  known  length  of  the  joint  above  x; 
h  =  the  depth  of  a  course  of  masonry  assumed  as  10  feet; 
w  =  the  distance  of  P'  from  the  back  edge  of  the  joint  /; 

ds 

M  =  —  =  the  moment  of  H  on  the  joint  x; 
6r 

ff 

H  =  —  =  the  horizontal  thrust  of  the  water. 
2r 

Equation  (2)  may  be  used  for  a  series  of  joints  down  to  a 
depth  where  the  back  surface  of  the  dam  begins  to  slope  or  until 

/Y* 

a  joint  is  found  where  n  =  —  ;   n  being  the  distance  of  P'  from 

o 
the  back  edge  of  the  joint  x.     For  the  next  course  both  faces 

sy* 

will  have  to  be  sloped,  and  u  =  n——t  when  we  obtain 

o 

6M 


In  applying  equation  (3)  for  finding  the  value  of  x,  the  maxi- 
mum pressure  must  be  obtained  both  with  reservoir  full  and 
empty.  This  may  be  done  by  the  formula 

6M 

**=—,     ...      ...  -     (4) 

in  which  p=  the  limiting  pressure  per  square  foot  at  the  front 
face  of  the  dam.  This  equation  may  be  employed  until  the 
limiting  pressure  is  reached  at  the  back  face,  when  the  following 
formula  must  be  used: 


MOLESWORTH'S  FORMULA  AND  PROFILE  TYPE      409 

.      .  (5) 


in  which  q  is  equal  to  the  limiting  pressure  per  square  foot  at 
the  back  face  of  the  dam,  and  is  generally  assumed  to  be  greater 
than  p. 

These  equations  give  the  successive  lengths  of  the  joints, 
but  do  not  give  their  position.  This  may  be  found  by  deter- 
mining the  value  of  y=  the  batter  of  the  back  face;  the  formula 
being 

2W(x-3m)-h? 
6w  +  h(2l  +  x)  ' 
and  for  equation  (5), 

lh(x—l)  +  x2(h—q) 


h(2l  +  x) 

The  theoretical  profile  resulting  from  calculating  the  dam 
by  the  above  formula  will  have  polygonal  faces.  It  only  be- 
comes necessary  then  to  make  the  value  of  h  sufficiently  small 
to  determine  a  profile  with  a  smooth  surface  which  will  fulfil  all 
of  the  conditions. 

322.  Molesworth's  Formula  and  Profile  Type.  —  Mr.  Guil- 
ford  L.  Molesworth  has  worked  out  the  following  formula,  the 
application  of  which  gives  the  profile  shown  in  Fig.  154: 


This  formula  gives  a  dam  of  excellent  cross-section  nearly  ap- 
proaching that  gotten  by  Wegmann's  and  others,  and  one  in 
which  the  resultants  of  pressures,  reservoir  full  and  empty,  lie 
well  within  the  middle  third.  The  computations  by  this  formula 
are  simple,  and  for  that  reason  it  is  given  here. 

3>  =  the  distance   measured  along  any  point   in   the  masonry 
from  the  down-stream  face  to  a  vertical  line  drawn  from 
the  top  front  edge  of  the  dam  to  the  base; 
2  =  the  corresponding  distance  on  the  same  joint  to  the  up- 

stream face; 

#  =  the  distance  from  the  top  of  the  dam  to  the  joint  above 
mentioned  ; 


4io  MASONRY   DAMS 

y  =  .6oc  as  a  minimum; 

r  =  the  limit  of  pressure  of  the  masonry  in  tons  per  square  foot ; 
H  =  the  minimum  height  of  dam  in  feet; 

TT 

a  =  y  at — from  the  top; 

4 

b  =  top  width  =  -. 

323.  Height  and  Top  Width  of  Dam. — As  far  as  the  forces 
already  considered  are  concerned,  the  top  width  of  the  dam  might 
be  zero  and  the  water  might  rise  to  its  crest.     In  practice  a  certain 
definite  top  width  must  be  given  in  order  to  enable  the  dam  to 
withstand  the  shock  of  waves  and  ice,  and  the  top  of  the  dam  must 
be  continued  above  the  maximum  flood-water  line  for  a  sufficient 
height  to  prevent  its  being  topped  by  waves.     Ordinarily  the  top 
width  of  the  dam  should  be  sufficient  to  enable  it  to  act  as  a  road- 
way and  afford  communication  between  the  two  slopes  of  the 
valley.     It  should  never  be  less  than  5  or  6  feet,  and  for  the  highest 
dams  need  never  exceed  15  feet,  varying  between  these  according 
to  the  height  of  the  wall. 

Having  calculated  the  height  of  the  dam  for  maximum  flood 
heights  of  water,  this  should  be  continued  upward  a  sufficient 
amount  to  insure  it  against  being  topped  by  the  waves.  The 
height  of  waves  depends  on  complex  causes,  chiefly  on  the  depth 
of  the  reservoir  and  the  fetch,  a  formula  for  computing  which 
was  given  in  Article  305.  The  maximum  amount  to  which  it 
will  be  necessary  to  increase  the  computed  height  of  the  dam  need 
rarely  or  never  exceed  10  feet,  its  minimum  being  as  low  as  one 
foot  in  an  extremely  shallow  and  small  reservoir.  On  top  of 
the  crown  of  the  dam  there  should  always  be  a  parapet  as  an 
additional  precaution  against  its  being  topped  by  waves,  and 
this  parapet  may  be  from  3  to  5  feet  in  height. 

324.  Profile  of  Dam. — In  Fig.  155  is  given  a  comparison  of 
the  profiles  obtained  by  several  of  the  more  common  formulas, 
while  that  which  is  shown  in  full  lines  is  the  practical  profile 
type  No.  3,  adopted  by  Wegmann.     In  the  table  on  the  oppo- 
site page  are  given  the  dimensions  and  pressures  for  this  profile 


STABILITY  AGAINST  UPWARD   WATER  PRESSURE       411 

type.     The  specific  gravity  of  the  masonry  employed  in  making 
these  computations  is  assumed  at  2\. 

325.  Stability  against  Upward  Water  Pressure;  also  Causes 
of  Failure.— The  question  of  the  effect  of  springs  under  founda- 
tions of  masonry  dams  is  still  an  open  one,  and  has  led  to  much 
discussion  among  the  more  experienced  builders  of  such  struc- 


'.so  x-9       .  z  _  /.ooa?\*;   . 

a  =  y  at  ^-;  6  -•  .4  a  *,  y  «- 0.6  X  as  a  minimum; 

H  —  Height  of  dam  in  feet; 

Xs*  Depth  in  feet  of  any  horizontal  plane  below  >rW.L, 
—  Offset  in  feet  from  vertical  line,  A-A  to  outer  face  of 

dam  at  any  depth  X ; 
Z  =  Offset  to  inner  face ; 
b  =  Width  in  feet  of  dam  at  top; 

Limit  of  pressure  in  tons  per  square  foot; 


—  7.492-I 38.02 " »JSO 


Scaled 
FIG.  154. — Molesworth's  Profile  Type. 

tures.  A  cross-section  which  would  enable  a  dam  to  resist  up- 
ward water-pressure  should  be  much  heavier  than  one  called  for 
by  the  usually  accepted  theories  which  disregard  such  pressure. 
It  would,  in  fact,  be  nearly  twice  as  heavy,  and  therefore  call  for 
about  twice  as  much  masonry  in  the  structure  as  would  the  theo- 
retical cross-section.  All  the  evidence  appears  to  be  against 
danger  of  rupture  from  such  causes.  There  have  been  con- 
structed and  are  still  standing  many  masonry  dams  designed  on 


412  MASONRY  DAMS 

cross-sections  too  light  to  withstand  theoretical  pressures  from 
below,  and  of  all  these  structures  but  three  of  any  moment  have 
failed,  namely,  the  Puentes,  Habra,  and  Bouzey  dams;  and 
the  causes  of  failure  of  each  of  these  has  been  due  to  faulty  con- 
struction rather  than  to  errors  in  not  designing  an  ample  profile 
for  withstanding  upward  pressure.  In  a  recent  discussion  of  this 


Scale  of  Feet 


\        0  5  10    20     30    40     50    60     70 


Delocre's  Type 

Kankine's     " 

Krantz's       ft 

~ Crugnola's    " 

Quaker  Bridge  Dam 

Wegmanri's  Type 


Krantz-  Delocre    Crugnola 


QuakerJridge  Dam 


\ 
v 

\ 


FIG.  155.  —  Comparison  of  Profile  Types. 


subject  before  the  American  Society  of  Civil  Engineers  Mr.  Weg- 
mann  enumerates  the  causes  of  failure  in  these  three  structures  as 
follows  : 

The  Puentes  dam,  built  in  Spain  a  century  ago,  was  164  feet 
high.     During  construction  a  deep  pocket  of  earth  was  discov- 


STABILITY   AGAINST  UPWARD  WATER  PRESSURE          413 


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jo    do^  M.O\ 
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414  MASONRY   DAMS 

ered  under  the  foundation,  and  instead  of  going  down  to  solid 
rock  a  pile  foundation  was  employed  in  this  place.  This  was 
forced  outward  by  water-pressure  and  caused  a  rupture  in  the 
cement  portion  of  the  dam.  The  Habra  dam,  constructed 
twenty-five  years  ago,  failed  through  the  poor  material  used  in 
its  construction.  This  consisted  of  porous  sandstone  not  of 
uniform  character,  while  the  sand  used  in  the  cement  was  of 
poor  quality;  the  hydraulic  lime  was  made  of  calcareous  stone 
of  imperfect  quality  containing  quicklime,  which  possibly  ex- 
panded, and  thus  assisted  in  making  the  structure  porous. 
The  dam  was  not  water-tight,  for  water  flowed  through  it  like 
a  sieve,  until  finally  a  severe  rain-storm  caused  the  structure  to 
be  overtopped  by  a  flood  13  feet  in  height  above  the  crest,  which 
resulted  in  its  destruction.  The  Bouzey  dam  was  completed 
ten  years  ago  and  was  founded  on  porous  conglomerate  rock; 
consisting  of  siliceous  stones  joined  together  by  poor  cement 
material.  The  foundation  was  not  carried  down  to  solid  rock, 
and  to  prevent  leakage  under  the  dam  a  guard-wall  6J  feet  thick 
was  carried  below  the  main  structure  for  a  depth  of  20  or  30  feet 
to  solid  rock.  As  the  maximum  height  of  water  in  the  reservoir 
was  to  be  75  feet,  this  guard-wall  could  scarcely  be  expected 
to  prevent  water  from  percolating  under  the  dam,  and  thus  cause 
sufficient  upward  pressure  to  injure  its  stability  by  sliding.  The 
structure  was  finally  ruptured,  not  by  settling  or  overturning, 
but  by  sliding  or  bulging  forward,  which  produced  numerous 
fissures  in  the  foundation  and  four  vertical  fissures  in  the  wall. 
In  this  latter  case  upward  pressure  under  the  base  caused  the 
disaster,  but  this  doubtless  would  not  have  occurred  had  the 
whole  dam  been  founded  on  solid  rock,  as  should  have  been 
the  case. 

In  the  construction  of  most  masonry  dams  fissures  are  en- 
countered in  the  foundation  rock  from  which  water  issues  or 
is  expected  to  issue  under  pressure.  These  should  invariably 
be  carefully  examined,  cleaned  out,  and  followed  down  to  such 
a  depth  as  to  reach  homogeneous  rock,  or,  after  being  cleaned 
out  for  a  considerable  depth,  should  be  gradually  narrowed  up 
with  cement  so  as  to  coax  leakage  water  to  a  small  orifice,  which 


STABILITY  AGAINST  TEMPERATURE  CHANGES  415 

may  terminate  in  a  tube  and  be  led  out  of  the  structure  or  be 
capped  and  bottled. 

326.  Stability   against    Temperature   Changes. — Mr.    George 
Y.  Wisner  has  called  attention  to  the  fact  that  strains  arising  from 
changes  in  temperature  in  straight  dams  are  sometimes  enormous 
and  must  be  provided  against  with  large  coefficients  of  safety. 
The  base  of  a  dam,  being  massive  and  generally  submerged  in 
water,  has  much  less  range  of  temperature  than  the  upper  por- 
tions of  the  structure,  where  it  may  exceed  100  degrees  F.     The 
expansion  of  sandstone  for  100  degrees  change  of  temperature 
is  about  i  inch  in  100  feet,  of  limestone  about  i  inch  in  125  feet, 
of  granite  about  i  inch  in  1 70  feet,  and  of  masonry  and  concrete 
may  average  i  inch  in  125  feet.     A  dam  500  feet  long  in  pass- 
ing through  a  change  of  100  degrees  temperature  will  expand  or 
contract  about  4  inches  in  its  entire  length,  and  will  subject  the 
upper  portion  of  the  wall  to  greater  strains  than  those  due  to 
water  pressure  and  weight  of  dam.     A  drop  of  20  degrees  of 
temperature  at  the  crest  of  the  dam  may  cause  a  tensile  strain 
of  40  tons  per  square  foot,  and  unless  the  dam  were  supported 
by  arch  construction,  it  would  be  left  with  only  its  resistance  to 
shearing  and  sliding  to  withstand  the  water  pressure. 

Mr.  Wisner  observes  that  if  the  upper  portion  of  the  dam 
be  constructed  during  a  period  of  warm  weather,  the  arch  will 
be  under  tension  during  the  cooler  portions  of  the  year  and  a 
large  portion  of  the  pressure  from  the  water  will  be  transmitted 
to  the  toe  of  the  dam.  On  the  other  hand,  if  the  walls  be  con- 
structed in  cool  weather,  the  arch  will  be  under  compression 
most  of  the  time,  and  the  water  pressure  will  be  transmitted 
directly  to  the  side  walls  by  the  arch.  In  most  cases  for  curved 
dams  of  less  than  500  feet  length  on  the  crest,  the  cross -sect  ion 
necessary  to  keep  pressure  on  the  foundation  within  sufficient 
limits  is  ample  to  withstand  shearing  stress  from  water  pressure, 
thus  making  the  curved  type  of  dam  for  the  same  stability  much 
more  economical  than  that  of  gravity  section. 

327.  Curved  Masonry  Dams. — A  dam  of  the  kind   already 
considered  is  of  the  pure  gravity  type  and  relies  for  its  stability 
solely  on  the  weight  of  the  masonry  and  its  friction.     A  dam 


4T6  MASONRY  DAMS 

of  the  pure  arched  type  relies  solely  on  the  arched  form  for  sta- 
bility, in  which  case  the  pressure  of  the  water  is  transmitted 
laterally  to  the  abutments.  If  our  knowledge  of  the  laws  govern- 
ing masonry  arches  were  more  complete,  the  arched  or  curved 
dam  would  probably  be  the  best  type,  since  it  will  contain  the 
least  amount  of  material.  As  it  is,  we  know  something  of  the 
laws  governing  such  true  masonry  arches  as  those  supporting 
bridges.  In  these  the  two  extremities  of  the  arch  are  raised 
at  their  springing  on  some  firm  abutment  and  the  whole  is  keyed 
together  at  the  center;  but  in  a  masonry  dam  of  arched  form 
not  only  is  the  arch  supposed  to  transmit  the  pressures  laterally 
to  the  side  of  the  abutments,  but  as  the  dam  rests  on  the  bottom 
of  the  valley  it  is  sustained  again  at  that  point,  so  that  it  cannot 
act  as  a  true  arch, — nearly  perfect  arch  action  only  occurring 
at  the  top,  where  the  pressure  is  a  minimum,  while  near  the  bottom, 
where  the  pressure  is  greatest,  probably  very  little  of  this  is  trans- 
mitted to  the  abutments.  For  this  reason  it  is  not  yet  considered 
safe  to  build  a  dam  depending  purely  on  the  arched  form,  and 
such  few  dams  as  have  been  constructed  on  this  principle  have 
been  given  somewhat  of  the  gravity  cross-section,  increasing 
downward  in  width,  so  that  they  presumably  resist  the  pressure 
both  by  gravity  and  arched  action.  The  best  existing  types  of 
such  works  are  the  Zola  dam  in  France,  the  Shoshone  and  Path- 
finder dams,  Wyoming,  and  the  Bear  Valley  and  Sweetwater  dams 
in  California  (Arts.  352,361,  and  362). 

That  a  masonry  dam  constructed  across  a  narrow  valley 
can  resist  the  water-pressure  by  transmitting  it  to  its  abutments 
is  proved  by  the  dams  above  cited.  The  question  then  arises, 
can  the  profile  be  reduced  from  what  would  be  required  if  the 
plan  was  straight?  As  stated  at  the  beginning  of  this  chapter, 
Krantz  asserts  that  a  dam  curved  in  plan  and  convexed  up- 
stream with  a  radius  65  feet  or  less  will  transfer  the  pressure  of 
the  water  to  its  abutments.  Dams,  however,  of  even  greater 
radius  than  this  do  transfer  the  pressure  to  the  abutments.  The 
radius  of  the  Zola  dam  is  158  feet  and  its  length  on  top  is  205 
feet.  The  length  of  the  Bear  Valley  dam,  which  depends  almost 
wholly  on  its  arched  form  for  its  stability,  is  230  feet,  the  radius 


CURVED  MASONRY    DAMS 


417 


at  the  top  being  335  feet  and  at  the  bottom  226  feet.  The  Sweet- 
water  dam  is  380  feet  in  length  on  top,  its  radius  at  the  same  point 
being  222  feet.  The  Shoshone  dam  is  200  feet  in  length  on  top, 
the  radius  of  curvature  of  its  center  line  being  150  feet.  M.  Delo- 
cre  says  that  a  curved  dam  will  act  as  an  arch  if  its  thickness  does 


SCALE    OP 
OS     10    15  ?0 


*3-» . aj.od...... 3?.?3 


FIG.  156. — Practical  Profile  from  Wegmann. 


200 


not  exceed  one-third  of  the  radius  of  its  up-stream  or  convex  side. 
M.  Pelletreau  fixes  the  limiting  value  of  the  thickness  at  one-half 
of  this  radius.  When  a  dam  acts  as  an  arch  it  only  transmits  the 
water-pressure  to  the  sides  of  the  valley;  its  own  weight  must  still 
be  borne  by  the  foundation. 
27 


41 8  MASONRY    DAMS 

328.  Design  of  Curved  Dams. — Mr.  Wegmann  gives  the 
following  formula  for  calculating  the  thrust  in  curved  dams  of 
circular  plan : 

t  =  pr, 
in  which  t  =  the  uniform  thrust  in  the  circular  rings  of  any  plane 

of  the  masonry; 
p  =  the  pressure  per  unit  of  length  of  this  section  of  the 

ring; 

r  =the  radius  of  the  rings  of  the  outer  surface. 
Arch  action  can  only  take  place  by  the  elastic  yield  of  the  masonry; 
but  little  is  known  of  the  elasticity  of  brick,  stone,  etc.,  and 
nothing  of  the  elasticity  of  masonry;    hence  it  is  impossible  to 
determine  the  amount  of  the  arch  action. 

It  may  be  shown  theoretically  that  in  the  case  of  a  narrow 
valley  a  profile  of  less  area  may  be  employed  for  a  dam  which 
is  curved  in  plan  than  for  one  in  which  the  plan  is  straight.  An 
excellent  theoretical  discussion  of  this  subject  has  been  pub- 
lished by  Messrs.  Hubert  Vischer  and  Luther  Wagoner.  The 
result  of  the  investigations  of  these  gentlemen  goes  to  show 
that  arch  action,  as  usually  understood,  adds  little  to  the  strength 
of  a  curved  dam.  Notwithstanding  this,  the  curved  form  may 
to  a  marked  degree  afford  additional  resistance,  and  this  in  a 
manner  less  dependent  on  the  radius  of  the  curve  than  the  arched 
theory  implies.  The  general  conclusion  reached  by  these  gentle- 
men is,  further,  that  the  rate  of  efficiency  of  a  curved  dam  over 
the  straight  decreases  with  the  increased  length  of  the  dam; 
that  very  narrow  cross-sections  are  not  justifiable;  and  they 
ascribe  the  high  duty  of  the  Bear  Valley  dam  to  a  favorable  com- 
bination of  conditions  which  could  not  have  held  good  if  the 
span  had  been  considerably  longer  or  the  workmanship  less 
excellent. 

Engineers  are  now  fully  agreed  upon  the  advantages  of  the 
curved  plan.  Its  chief  disadvantage  is  the  increased  length  of 
the  dam  over  a  straight  plan,  and  the  consequent  increase  in  the 
amount  and  cost  of  material  to  within  certain  limits  of  top  length 
and  radius.  Though  the  cross-section  of  a  curved  dam  may 
unquestionably  be  somewhat  reduced,  it  would  be  unsafe  to 


DESIGN    OF   CURVED   DAMS  419 

reduce  it  as  much  as  has  been  done  in  the  case  of  the  Bear  Valley 
and  Zola  dams,  without  adding  metal  reinforcement,  though  these 
have  withstood  securely  the  pressures  brought  against  them.  It 
might  with  safety  be  reduced  under  favorable  conditions  to  the 
dimensions  of  the  Sweetwater,  or  Shoshone  dams,  thus  saving 
largely  in  the  amount  of  material  employed.  All  of  the  more 
conservative  writers,  as  Wegmann,  Rankine,  and  Krantz,  recom- 
mend that  the  design  of  the  profile  be  made  sufficiently  strong 
to  enable  the  wall  to  resist  water  pressure  simply  by  its  weight, 
and  to  curve  the  plan  as  an  additional  safeguard  whenever  the 
topography  makes  it  advisable.  American  engineers,  and  es- 
pecially those  of  the  West,  however,  are  prone  to  be  more  liberal ; 
and  the  tendency  is  toward  a  slight  reduction  in  the  cross-section 
where  a  curved  plan  is  practicable,  as  shown  in  the  great  dams  of 
the  Reclamation  Service.  An  additional  advantage  of  the  arched 
form  of  dam  is  that  pressure  of  the  water  on  the  back  of  the  arch 
is  perpendicular  to  the  up-stream  face,  and  is  decomposed  into 
two  components,  one  perpendicular  to  the  span  of  the  arch  and 
the  other  parallel,  to  it.  The  first  is  resisted  by  the  gravity  and 
arch  stability,  and  the  second  thrusts  the  up-stream  face  into 
compression,  which  has  a  tendency  to  close  all  vertical  cracks 
and  to  consolidate  the  masonry  transversely. 

An  excellent  manner  in  which  to  increase  the  efficiency  of 
the  arch  action  in  a  curved  dam  is  that  employed  in  the  Sweet- 
water  dam,  in  California.  This  consists  in  reducing  the  radius 
of  curvature  from  the  center  towards  the  abutments.  The  good 
effect  of  this  is  to  widen  the  base  or  spring  of  the  arch  at  the  abut- 
ments, thus  giving  a  broader  bearing  for  the  arch  on  the  hillsides. 
In  the  Sweetwater  dam  the  effect  of  this  is  seen  in  projections  or 
rectangular  offsets  made  on  the  down-stream  face  of  the  dam 
(PI.  XXVII),  the  center  of  the  dam  sloping  evenly,  while  the 
surface  is  broken  by  steps  where  it  abuts  against  the  hillside. 

The  best  materials  for  a  dam  of  curved  type  is  probably  a 
wall  having  a  face  of  first-class  masonry  with  center  filling  of  con- 
crete and  large  rock.  Such  a  dam  will  consist  practically  of 
two  concentric  arches  capable  of  withstanding  heavy  pressures, 
connected  by  a  water-tight  concrete  core,  having  a  lower  modulus 


420  MASONRY    DAMS 

of  elasticity.  In  the  case  of  high  dams  of  considerable  length, 
the  use  of  railroad  iron  in  the  upper  portion  of  the  structure  may 
"  prevent  temperature  cracks.  Construction  when  temperatures  are 
below  normal,  thus  insuring  compressive  strains  most  of  the 
time,  will  have  a  similar  effect. 

329.  Wide-crested  or  Overfall  Dams. — Gravity  dams   (Art. 
316)    are    designed    with    cross-sections    sufficiently    ample    to 
enable  them  to  resist  by  their  weight  the  hydrostatic  forces 
which  tend  to  overturn  or  slide  them.     Curved  dams  (Art.  327) 
are  designed  to  resist  the  same  forces,  but  their  weight  is  aided 
in  that  effort  by  curving  them  in  plan  in  such  manner  as  to  add 
to  their  stability  by  bringing  into  play  arch  action.     They  are 
sometimes  accordingly  diminished  in  cross-section  from  gravity 
requirements.     Overfall  dams  have  to  resist,  in  addition  to  the 
hydrostatic  forces  tending  to  shear  or  overturn  them,  the  dy- 
namic and  erosive  action  due  to  having  large  volumes  of  water 
pour  over  them,  often  from  great  heights.     Their  cross-sections 
must  therefore  be  increased  over  those  called  for  by  gravity 
requirements  by  an  amount  sufficient  to  enable  them  to  resist 
the  pounding  and  erosive  action  of  the  falling  water.     This  re- 
sult is  usually  aided  by  diminishing  these  forces  to  some  extent 
by  giving  their  lower  slopes  such  rollerway  curves  (Art.  176)  as 
will  cause  the  water  to  slide  or  roll  down  them  rather  than  fall 
and  be  broken  up  on  them;    also,  by  diminishing  the  effective 
height  of  overfall  by  water-cushions,  as  is  done  for  weirs  (Art. 

177). 

An  overfall  dam  therefore  has  to  withstand  greater  destruc- 
tive forces  than  any  other  type,  and  should  accordingly  be  con- 
structed of  even  better  materials,  with  greater  care,  and  be  if 
possible  more  firmly  founded  than  a  simple  gravity  dam  of  cor- 
responding height.  The  cross-sections  of  existing  overfall  dams 
exhibit  on  the  one  hand  the  conservatively  massive  English 
type  illustrated  by  the  Vyrnwy  dam  (Fig.  168),  and  on  the  other 
the  bold  Western  type  illustrated  by  the  La  Grange  dam  (Fig.  171) 
which  is  scarcely  heavier  than  gravity  alone  would  require.  In 
both  of  these  examples  well-designed  rollerway  curves  and  deep 
water-cushions  greatly  reduce  the  erosive  effect  of  the  falling 


DESIGN    OF    OVERFALL    DAMS  421 

water.  Between  these  extremes  the  Folsom  dam  (PL  XXXI) 
is  amply  heavy  and  has  a  good  lower  curve,  but  too  wide  and 
sharp  a  crest  to  produce  the  best  results.  The  Betwa  dam  (Fig. 
170),  while  having  a  cross-section  at  variance  with  the  theoretic 
demands  upon  it,  is  made  very  heavy,  with  a  massive  buttress 
below  to  reinforce  it.  The  form  of  overfall  given  the  new  Croton 
weir  (Fig.  165)  is  more  nearly  that  required  by  theory,  but  the 
advisability  of  breaking  its  lower  face  up  into  steps  is  doubtful, 
for  this  prevents  its  rollerway  curve  from  causing  the  water  to 
slide  gently  down  it,  while  it  induces  a  strong  erosive  action  on 
the  face  of  the  dam,  though  it  reduces  the  action  at  the  toe. 
Probably  the  best  cross-section  yet  given  an  overfall  dam  is  that 
given  the  Spier  Falls  dam  (Fig.  173),  and  the  McCall's  Ferry 
dam,  the  curves  of  the  lower  faces  of  which  are  such  as  to  aid  best 
in  producing  a  sliding  motion  in  the  falling  water,  while  the  crest 
width  is  neither  too  great  nor  too  little. 

330.  Design  of  Overfall  Dams. — As  yet  theory  has  made 
little  advance  in  solving  the  proper  cross-section  for  overfall 
dams.  We  believe  that  they  should  be  somewhat  more  mas- 
sive than  gravity  sections,  and  that  their  lower  slopes  should 
be  so  modified  as  either  to  cause  the  water  to  slide,  as  in  the 
Colorado  River  dam,  or  fall  clear  of  the  base,  as  in  the  Betwa 
dam.  We  know  that  the  provision  of  a  water-cushion  tends 
materially  to  reduce  the  erosive  and  dynamic  action  of  the  fall- 
ing water  by  reducing  the  height  of  fall.  On  the  other  hand, 
the  form  of  the  crest  and  that  of  the  lower  slope  are  still  points 
of  difference  among  hydraulic  engineers.  There  are  those  who 
favor  a  very  wide  crest  with  a  sharp  lower  edge  as  giving  the 
proper  direction  to  a  body  of  falling  water;  there  are  others 
who  favor  the  curved  crest  and  lower  face;  and  still  others  who 
advocate  the  stepped  outer  slope. 

Again,  instances  are  not  lacking  in  which  an  unprecedented 
flood  has  proven  too  great  for  the  wasteway  of  a  simple  gravity 
dam,  and  large  volumes  of  water  have  passed  harmlessly  over 
its  crest.  This  has  happened  during  construction  to  the  Bhatgur, 
Tansa,  and,  in  our  own  country,  to  the  San  Mateo  dams;  while 
since  completion  the  more  frail  Sweetwater  curved  dam,  and 


422  MASONRY   DAMS 

lightest  of  all  the  Bear  Valley  dam,  have  been  harmlessly  topped 
by  flood -waters.  To  assume  from  this,  however,  that  such 
sections  are  sufficiently  substantial  for  overfall  dams  would  be 
unsafe,  and  no  careful  engineer  will  intentionally  tempt  fate  as 
yet  by  adopting  them  for  overfall  dams.  Again,  each  case  will 
require  special  treatment  and  its  own  dimensions,  according 
as  the  dam  is  to  be  topped  by  a  few  feet  of  water,  as  in  the  Croton 
overfall  weirs,  or  by  a  flood  which  banks  up  30  feet  above  the 
crest,  as  with  the  Folsom  dam. 

One  of  the  simplest  problems  connected  with  the  design  of 
wide-crested  overfall  dams  is  the  determination  of  the  velocity 
and  discharge  for  a  given  depth  of  water  passing  over  the  crest, 
yet  the  theoretic  determination  of  these  quantities  is  one  of  the 
most  difficult  problems  of  solution,  since  it  is  affected  by  the 
curves  at  both  the  upper  and  lower  edges  of  the  crest  as  well 
as  by  the  crest  width.  The  crest  velocity  may  be  accepted  as 
being  due  to  the  differences  in  head  over  the  dam  crest  between 
still  water  above  the  dam  and  high-water  surface  over  the  crest. 
Thus  (Fig.  157),  v  is  dependent  on  H — h,  and  may  be  expressed 

^£), (i) 


and  for  discharge  per  unit  of  length  in  second-feet 

-h),        ....     (2) 


<2  =  o  when  h  =  o  or  h  =  H.  In  formula  (2)  the  discharge 
Q  is  a  maximum  when  H  =  $/2h;  therefore,  for  maximum  dis- 
charge, 

......     (3) 


in  which  B  =  width  of  crest,  agrees  very  closely  with  the  results 
obtained  from  experiment. 

A  rounded  inner  edge  to  the  crest  prevents  crest  contrac- 
tions and  increases  the  discharge  greatly  in  proportion  to  the 
degree  of  rounding.  The  same  effect  is  produced  by  curving 
the  outer  edge,  the  tendency  of  which  is  to  diminish  the  width 
of  the  dam  crest  and  to  make  it  to  conform  more  nearly  to  the  dis- 
charge which  would  be  gotten  from  a  knife-edge  weir.  Width 
of  crest  and  degree  of  rounding  will  affect  accordingly  the  velocity 


DESIGN    OF    OVERFALL    DAMS 


423 


and  discharge,  and  will  determine  how  far  out  over  the  weir 
crest  the  column  of  water  will  fall  for  a  given  height.  Thus  a 
very  sharp  crest  well  rounded  on  the  outer  face  will  cause  the 
water  to  flow  or  slide  down  this  face  and  alight  upon  it  well 
within  the  toe;  a  broader  crest  less  curved  will  throw  the  water 


k 

Jfc: 


FIG.  157. — Flow  Over  Wide-crested  Dam. 


further  out  and  make  it  alight  nearer  the  toe,  thus  jarring  the 
structure;  while  a  very  wide  crest  with  sharp  outer  edge  may 
throw  the  water  out  entirely  clear  of  the  dam.  Francis'  formula 
of  flow  for  a  sharp-edged  weir  crest  (Art.  90),  that  is,  one  in  which 
B  equals  zero,  gives 

Q  =  3.goHVW. (4) 

If  the  crest  is  very  wide,  and  there  be  practically  no  curve  at 
either  edge,  the  stream  assumes  a  rectilinear  direction,  so  that 
the  formula  for  maximum  flow  in  a  canal  applies,  or 

Q  =  2.92HVlT, (5) 

which  will  not  apply  for  crest  widths  B  less  than  3.5^.  Accord- 
ingly, for  intermediate  widths,  the  constants  in  formulas  (4) 
and  (5)  will  have  values  intermediate  between  those  there  given 
(Art.  368). 

The  pressure  against  the  back  of  the  surcharged  masonry  dam, 
or  spillway,  is  represented  by 

P  =  d(2H  +  d)3i.2$, (6) 

in  which  P  is  the  pressure  and  d  the  total  depth  of  water  above 
inner  foot  of  dam.  The  center  of  pressure  g  is  on  the  line  pass- 
ing through  the  center  of  gravity  of  the  prism  of  water  pressing 
against  the  upper  face  of  the  dam,  and  is 


424  MASONRY    DAMS 


2H+d 

The  point  of  application  of  the  overturning  moment  M  about 
the  outer  toe  is  the  product  of  (6)  and  (7),  and  is 

M  =  io.42d2(sH  +  d)  .....     (8) 

331.  Foundations.  —  Masonry    dams    must    be    founded    on 
solid  rock,  and  great  care  and  judgment  are  required  in  deter- 
mining just  when  the  excavation  for  the  foundation  has  pro- 
ceeded sufficiently  far.     If  the  looser  and  partially  decomposed 
surface  rock  is  not  entirely  removed  there  is  danger  of  leakage 
under  the  dam,  and  consequent  liability  of  its  destruction.     If  the 
excavation  is  carried  too  far  into  the  underlying  rock  much  money 
may  be  wasted.     Frequent  cases  might  be  cited  where  it  has 
been  found  necessary  to  make  unusually  deep  excavations  in 
order  that  a  sufficiently  firm  foundation  might  be  reached.     In 
the  case  of  the  Turlock  dam  the  average  depth  of  excavation  in 
the  large  bowlders  and  underlying  porphyry  was  from  5  to  10 
feet  to  the  homogeneous  material.     In  one  or  two  cases,  how- 
ever, seams  full  of  huge  bowlders  weighing  several  hundred  tons 
apiece  were  encountered,   which  necessitated   excavation  to   a 
depth  of  25  to  35  feet  in  order  that  they  might  be  worked  out 
and  homogeneous  rock  reached.     A  masonry  dam  is  an  abso- 
lutely rigid  structure,  and  the  least  unequal  settlement  in  any 
portion  of  it  tends  to  produce  a  crack.     A  clay  or  hardpan  foun- 
dation is  almost  sure  to  yield  under  the  weight  of  a  masonry 
dam,  and  be  the  loose  material  ever  so  little  in  amount,  if  it  offers 
opportunity  for  subsidence  it  will  result  in  the  rupture  of  the 
dam.     The  safe  load  on  the  lower  courses  of  a  masonry  dam 
depends  on  the  character  of  the  material  of  which  it   is  com- 
posed,  and  may  reach  from  10  to  15  tons  per  square  foot,  and 
nothing  but  the  most  substantial  rock  will  bear  such  a  weight 
as  this. 

332.  Preparing    Foundation.  —  After    the    foundation    of    a 
masonry  dam  has  been  excavated  down  to  a  solid  or  homo- 
geneous rock  the  greatest  care  should  be  taken  in  properly  clean- 
ing it  and  roughing  its  surface  in  order  to  make  a  most  perfect 


PREPARING   FOUNDATION  425 

bond  with  the  masonry  superstructure.  Perhaps  the  best  way 
of  describing  the  care  to  be  taken  in  these  particulars  is  by  re- 
hearsing the  account  given  by  Mr.  Walter  McCulloh,  detailing 
the  excavation  for  the  foundation  for  the  Sodom  dam  of  the 
Croton  water  supply. 

The  rock  of  the  foundation  was  rotten,  disintegrated,  and 
shaly  for  a  depth  of  from  4  to  15  feet.  In  preparing  the  foun- 
dation, drilling  was  done  by  steam  and  hand,  and  light  charges 
of  40  to  60  per  cent  dynamite  used  in  blasting  until  the  rock 
appeared  firm.  Then  all  seams  and  fissures  were  followed 
up  with  block-hole  and  black-powder  blasting,  and  by  barring 
out  until  a  solid  and  practically  tight  bottom  was  secured.  The 
foundation  thus  prepared  was  swept  clean  with  wire  stable  brooms 
and  washed  thoroughly  with  streams  from  hose-pipes.  In  the 
process  of  washing  it  may  be  stated  that  streams  under  high 
pressure  are  desirable  in  order  to  remove  every  particle  of  loose 
material,  and  the  use  of  hot  water  or  steam  is  found  to  facilitate 
the  cleansing  of  the  foundation. 

When  the  bottom  of  the  foundation  for  the  Sodom  dam  was 
ready,  all  pockets,  holes,  and  seams  were  filled  with  rich  Port- 
land-cement concrete,  forming  a  series  of  level  beds  on  which  to 
build  up  the  rubble  superstructure.  The  use  of  concrete  beds 
was  discontinued  later,  as  it  was  found  that  a  tighter  bed  could 
be  formed  with  rubble  and  small  stones.  A  large  amount  of 
water  made  its  way  through  the  loose  rock  above  the  bottom, 
and  in  some  cases  through  seams  in  the  bottom  itself,  but  generally 
where  the  rock  appeared  solid  the  seams  were  not  followed  any 
deeper.  Springs  washed  the  mortar  out  of  the  concrete,  but 
in  making  the  rubble  beds  the  water  was  led  around  and  pre- 
vented from  doing  damage,  by  forcing  the  streams  from  place 
to  place,  until  finally  a  small  well  2  feet  in  diameter  and  from 
i  to  2  feet  deep  would  be  formed  about  the  place  where  the  water 
boiled  up.  When  the  mortar  about  each  well  was  thoroughly 
set,  it  was  bailed  out  and  quickly  filled  with  dry  mortar,  and 
on  top  of  this  a  large  stone  would  be  placed,  and  the  spring  was 
effectually  bottled.  This  same  process  was  followed  over  the 
entire  bottom  wherever  water  had  to  be  contended  with,  and 


426  MASONRY   DAMS 

after  the  first  6  feet  of  rubble  foundation  was  laid  no  difficulty 
was  experienced. 

To  assure  no  shattering  of  the  foundation  rock  from  blast- 
ing at  the  Olive  Bridge  dam  site,  Esopus  creek,  N.  Y.,  both 
faces  of  the  foundation  curtain-wall  were  first  channelled,  and 
the  intermediate  rock  then  blown  out  with  black  powder. 
This  curtain- wall  was  sunk  20  feet  below  the  level  of  the  founda- 
tion proper  and  is  20  feet  wide,  to  assure  good  bond  and  cut  off 
seepage.  The  foundation  was  explored  with  drill  holes  in  which 
water  was  forced  and  all  seams  in  the  rock  thus  located  were 
closed  with  grout  pumped  in  under  pressure. 

Plate  XXIV  illustrates  admirably  the  great  depth  to  which 
foundations  are  sometimes  carried.  This  shows  the  founda- 
tion of  the  gate  chambers  of  the  new  Croton  Aqueduct  at  Cornell's, 
which  extend  in  places  to  a  depth  as  great  as  80  feet  below  the 
level  of  the  river-bed. 

333.  Material  of  which  Constructed. — Masonry  reservoir  dams 
may  be  built  of  cut  ashlar  stone;  of  rubble;  of  concrete  with  or 
without  dressed-stone  facing;  or  of  random  rubble  stone.  The 
first  is  best  on  account  of  its  strength,  but  while  only  twice  as 
strong  as  rubble,  it  costs  three  or  four  times  as  much.  As  the 
form  of  the  upper  part  of  the  dam  depends  on  the  positions  of 
the  lines  of  pressure  and  not  on  the  strain  in  the  masonry,  the 
great  strength  of  cut-stone  work  would  only  avail  in  the  lower 
portion  of  the  dam.  Great  care  would  have  to  be  employed  in 
the  use  of  cut  masonry  in  order  that  it  should  not  be  laid  in  hori- 
zontal beds,  which  might  permit  of  shearing  or  sliding,  and  in 
order  that  it  should  break  joints  with  a  proper  degree  of  irregular- 
ity. Neither  the  vertical  nor  the  horizontal  joints  in  a  dam  should 
be  continuous,  but  should  be  carefully  broken. 

Rubble  or  concrete  with  cut-stone  facing  is  not  a  desirable 
material  of  which  to  construct  a  dam,  because  of  the  difference 
in  settling  of  the  two  kinds  of  masonry,  which  might  result  in 
the  formation  of  cracks  and  seams.  Where  the  facing  becomes 
detached  in  this  manner  from  the  remainder  of  the  body  of  the 
wall  the  strength  of  the  structure  is  reduced  to  that  of  the  un- 
coursed  or  concrete  center.  The  most  prominent  examples  of 


PLATE  XXIV. — Excavating  Foundation  for  New  Croton  Dam  and  Gate-house. 


428  MASONRY   DAMS 

the  use  of  cut-stone  facing  with  rubble  or  concrete  interior  are 
to  be  found  in  the  Vir,  Bhatgur,  and  Betwa  dams  of  India,  which 
are  briefly  described  in  Articles  346  and  355,  and  the  new  Croton 
dam  in  New  York  (Art.  347).  In  each  of  these  the  cut  stone 
is  laid  as  headers  and  stretchers,  and  the  former  are  well  bonded 
into  the  mass  of  the  dam. 

334.  Concrete. — Concrete  has  been  successfully  employed  in 
five  of  the  greatest  dams  yet  constructed,  namely,  the  San  Mateo 
dam  in  California,  170  feet  in  height;  the  Periar  dam  in  India, 
(Art.  348),  155  feet  high;  in  the  Geelong  and  Beetaloo  dams  in 
Australia,  respectively  60  and  no  feet  in  height  (Article  349),  and 
in  the  McCalPs  Ferry  dam,  the  greatest  of  overfall  masonry  dams, 
60  feet  high.  The  Periar  and  Beetaloo  dams  are  two  of  the  best 
examples  of  the  homogeneous  use  of  concrete.  The  great  dis- 
advantage in  using  this  material,  aside  from  engineering  considera- 
tions, is  the  added  cost  of  cement  where  the  latter  is  expensive. 
The  great  advantage  of  the  use  of  concrete  is  the  saving  effected 
in  labor  and  the  speed  of  construction;  for  concrete  can  be  mixed 
and  handled  entirely  by  machinery  worked  by  water-power.  In 
the  Beetaloo  dam  for  46  feet  above  the  foundation  the  concrete 
was  made  of  i  part  Portland  cement,  2  parts  washed  sand,  and 
4  parts  broken  stone  of  2 -inch  gauge.  In  the  McCall's  Ferry 
dam  the  proportions  were  i  cement,  3  sand,  and  5  broken  stone 
of  sizes  up  to  5  inches.  This  concrete  was  laid  so  wet  as  to  require 
no  tamping.  In  building  such  structures  great  care  is  taken  to 
have  the  surface  of  the  set  concrete  picked,  washed,  and  brushed 
before  a  fresh  layer  is  deposited,  and  large  projecting  stones  are 
left  to  assist  the  bond.  Beetaloo  dam  was  built  up  as  a  monolithic 
mass,  the  concrete  being  laid  between  boards  or  framing  bolted 
in  the  body  of  the  dam.  The  concrete  for  McCall's  Ferry  dam 
was  laid  in  movable  steel  forms  of  wooden  lagging  boxes  between 
frameso 

Concrete  is  little  more  than  uncoursed  rubble  reduced  to  its 
simplest  form.  As  regards  resistance  to  crushing  or  percola- 
tion the  value  of  the  two  materials  is  almost  identical,  unless  it 
be  considered  as  a  point  in  favor  of  concrete  that  it  must  be  solid, 
while  rubble  may,  if  the  supervision  be  defective,  contain  void 


CONCRETE 


429 


spaces  not  filled  with  mortar.     The  selection  between  the  two 
depends  entirely  on  their  relative  cost. 

The  San  Mateo  dam  in  California  was  not  built  up  as  a  mono- 
lithic mass  of  concrete  as  were  those  just  described,  but  is  com- 
posed of  great  concrete  blocks  of  uniformly  irregular  dimensions. 
These  blocks  (PL  XXIV)  weigh  about  300  tons  each,  and  were 
built  up  in  the  body  of  the  dam  in  such  manner  as  to  key  in 
with  each  other  both  in  horizontal  and  vertical  plan,  so  as  to 
produce  a  nearly  homogeneous  mass  and  create  the  greatest 
amount  of  friction  between  blocks.  The  material  was  mixed  at 


-Double  Lacing 


Bar. 


This  Furring  Piece  to  t» 
1,12'C ;  15  It*,  with  Back, 
turned  toward*  Maaoory 


SIDE  ELEVATION 
FIG.  158. — Steel  Forms.     McCall's  Ferry  Dam,  Susquehanna  River,  Perm. 

the  site  of  the  dam,  and  run  out  in  a  tramway  and  built  in  place 
inside  of  a  wooden  boxing  which  was  afterwards  removed.  The 
blocks  were  left  surrounded  by  the  boxing  for  one  week,  during 
which  time  they  set  sufficiently  for  the  wood  to  be  removed  and  to 
permit  of  other  blocks  being  built  against  them.  The  concrete 
consisted  of  2 -inch  gauge  metal  mixed  in  the  proportion  of  6  of 
broken  stone  to  2  of  sand  and  i  of  Portland  cement. 

Concrete  should  be  laid  immediately  after  mixing,  and  should 


43°  MASONRY   DAMS 

be  thoroughly  rammed  and  compacted  until  the  water  flushes  to 
the  surface.  It  should  be  allowed  to  set  for  12  hours  or  more 
before  any  further  work  is  laid  upon  it. 

335.  Rubble  Masonry. — Rough  random  rubble   masonry   is 
perhaps  the  best  material  that  can  be  used  for  building  a  dam. 
It  possesses  strength,  can  be  readily  adapted  to  any  form  of 
profile,  and  is  relatively  cheap.     In  building  a  dam  the  main 
object  is  to  form  as  nearly  homogeneous  a  monolithic  mass  as 
possible.     Horizontal    and   vertical   courses    must   therefore    be 
avoided,  and  the  stones  interlocked  in  all  directions.     The  sizes 
of  these  stones  may  differ  greatly.     The  mass  of  the  wall  may 
be  composed  of  stones  of  such  a  size  as  may  be  carried  between 
two  men,  as  is  the  case  in  India,  where  machinery  is  rarely  em- 
ployed;   or  it  may  consist  of  cyclopean  rubble  measuring  from 
one  to  several  cubic  yards  in  volume,  each  block  perhaps  weighing 
several  tons,  as  in  the  Spier  Falls  dam.     To  prevent  leakage,  all 
spaces  between  the  stones  must  be  completely  and  compactly 
filled  with  impervious  mortar  or  cement.     To  prevent  sliding,  the 
blocks  must  be  irregularly  bedded,  and  as  each  course  is  laid  a 
large  proportion  of  the  stones  must  be  permitted  to  project  above 
the  general  surface.    The  spaces  between  the  larger  stones  may  be 
filled  with  concrete  or  small  rubble.     This  practice  of  imbedding 
cyclopean  rubble  in  concrete  is  becoming  increasingly  popular. 
Grouting  must  never  be  permitted,  and  the  best  stones  are  gener- 
ally reserved  for  the  facing,  in  which  they  are  laid  as  headers  in 
such  manner  as  to  give  an  even  contour  to  the  outer  surface. 

336.  Cement. — The  center  of  a  large  work  may  be  of  some 
cheaper  variety  of  cement,  as  Rosendale  or  other  natural  cement. 
Portland  cement  should  be  used  in  the  facing  stones  and  in  point- 
ing.    All  cement  used  should  be  hydraulic  and  of  some  well- 
known  brand,  whether  natural  or  Portland.     The  cement  should 
be  carefully  stored  in  a  tight  shed  with  a  close  floor  set  above  the 
ground  to  protect  it  against  dampness,  and  should  be  subjected  to 
strict  inspection  and  tests.     All  mortar  used  should  be  prepared 
from  the  best  quality  of  cement  of  the  kind  above  described,  and 
of  clean  sharp  river  sand  well  washed  and  free  from  dirt.     They 
should  be  mixed  dry  in  the  proper  proportions,  and  then  a  mod- 


DETAILS   OF    CONSTRUCTION  431 

erate  amount  of  water  should  be  added  and  the  whole  thoroughly 
worked  together.  Portland  cement  mortar  should  generally  be 
mixed  in  the  proportion  of  about  i  of  cement  to  2  of  sand  in  laying 
the  puddle  work;  while  for  laying  the  rubble  work  and  concrete 
i  of  cement  to  3  of  sand  may  be  used.  In  laying  masonry  great 
care  should  be  taken  that  water  shall  not  interfere,  and  in  no  case 
should  it  be  laid  in  water. 

337.  Details  of  Construction. — Rubble  stone  masonry  should 
always  be  made  of  sound  clean  stone,  of  suitable  size,  quality, 
and  shape  for  the  work.  All  awkward  projections  should  be 
hammered  off  so  that  the  stones  shall  become  rectangular  in 
form.  Their  beds  should  present  such  even  surfaces  that  when 
the  stones  are  lowered  on  the  surface  prepared  to  receive  them 
the  mortar  will  fill  all  spaces.  The  stones  should  be  well  rammed 
into  the  bed  of  mortar  if  they  axe  light,  and  this  should  be  at  least 
one  inch  in  thickness.  Where  large  stones  are  employed  a  moder- 
ate quantity  of  spawls  may  be  used  in  the  preparation  of  suitable 
surfaces  for  receiving  them.  Especial  care  must  be  taken  to  have 
beds  and  joints  full  of  mortar,  as  no  grouting  or  filling  of  joints 
should  be  allowed  after  the  stones  are  placed.  The  work  must  be 
thoroughly  bonded,  and  if  mortar  joints  are  not  full  and  flush  they 
should  be  taken  out  to  a  depth  of  several  inches  and  properly  re- 
pointed.  In  such  work  various  sizes  of  stones  should  be  employed 
and  regular  coursing  should  be  avoided  in  order  to  obtain  both 
vertical  and  horizontal  bonding.  The  sizes  of  the  stones  may  vary 
with  the  character  of  the  quarry,  but  where  the  thickness  of  the 
masonry  is  great  a  considerable  proportion  of  large  stones  should 
be  used.  Where  exceptionally  large  stones  are  employed  the 
joints  may  be  filled  with  concrete  instead  of  mortar  as  in  modern 
cyclopean  rubble  masonry.  In  such  cases  only  so  much  water 
should  be  employed  as  can  be  brought  to  the  surface  by  ramming. 

In  carrying  out  the  construction  of  rubble- masonry  work  it 
should  not  be  built  in  horizontal  courses;  at  the  same  time  it 
must  be  built  in  beds,  and  these  should  be  irregularly  stepped, 
and  various  parts  of  the  structure  worked  upon  and  allowed  to 
set  at  different  times.  The  surface  of  these  horizontal  steps  or 
courses  should  bristle  with  projecting  stones,  so  as  to  secure  a 


43  2  MASONRY  DAMS 

perfect  bond  in  every  direction.  This  is  done  by  working  up 
the  mortar  or  concrete  between  the  stones  to  about  half  their 
height,  and  wherever  the  work  is  stopped  over  night  or  for  a 
period  of  time  these  projections  insure  bond  with  the  next  layer 
to  be  worked.  No  stones  should  be  deposited  or  dressed  upon 
the  wall,  but  on  platforms  or  planking,  so  that  no  dirt  shall  be 
brought  in  contact  with  the  material.  The  same  precaution 
must  be  taken  in  handling  concrete  and  mortar. 

The  rubble  facing  stones  should  be  of  large  size,  not  less 
than  2  feet  deep,  with  frequent  headers.  Where  especial  jar  is 
brought  on  the  masonry  work,  as  in  overfall  weirs,  facing  stones 
should  be  of  range  rubble,  of  the  soundest  and  most  durable 
quality,  and  should  be  cut  so  true  that  joints  not  exceeding  J 
inch  shall  be  necessary  for  3  inches  from  the  surface,  the  remain- 
der of  the  joint  not  exceeding  2  inches  in  thickness  at  any  point. 
In  such  work  it  is  well  to  alternate  about  two  stretchers  for  one 
header,  and  to  make  the  former  not  less  than  3  feet  in  length, 
while  the  header  should  not  have  less  than  12  inches  lap  under 
ordinary  circumstances. 

The  concrete  used  in  work  of  this  character  should  be  made 
of  rough  broken  stone  metal,  and  of  clean  river  gravel  not  ex- 
ceeding from  2  to  2j  inches  gauge.  This  material  should  be 
washed  free  of  dirt  before  being  used,  and  be  mixed  in  boxes 
or  mortar  mixers  with  mortar  of  a  proper  quality.  The  pro- 
portions used  in  mixing  differ  greatly,  and  are  described  in  tech- 
nical books  treating  on  this  subject. 

After  cement  masonry  has  been  allowed  to  rest  until  it  has 
had  time  to  dry  and  harden  it  must  be  gone  over  with  sharp  picks 
or  chisel-edged  tools  to  remove  the  scale,  roughen  the  surface, 
and  make  it  clean  and  fresh  in  order  that  the  new  mortar  may 
adhere  to  it.  This  is  especially  true  of  new  work  laid  on  old 
which  has  set  for  several  months.  Masonry  should  not  be 
built  in  winter  during  freezing  weather  unless  exceptional  precau- 
tions are  taken  to  cover  and  protect  it  from  frost.  Recent  experi- 
ments with  masonry  built  in  freezing  weather  on  Sodom  dam 
showed  that  the  effect  of  freezing  was  not  as  serious  as  had  been 
anticipated,  though  no  mortar  was  set  in  temperatures  less  than 


DETAILS    OF   CONSTRUCTION  433 

+  20°  F.,  and  hot  brine  made  of  five  pounds  of  salt  to  one  pound 
of  water  was  used  for  mixing.  This  and  the  fact  that  the  sand 
and  stones  were  heated  is  believed  to  have  helped  the  quality 
of  this  cement.  In  addition,  salt  was  scattered  over  the  new 
work  at  night,  and  at  times  a  layer  of  sand  was  spread  over  to 
protect  it.  Masonry  laid  under  these  circumstances  showed  in 
the  spring  but  slight  damage  to  the  surface.  A  thin  scale  not 
exceeding  one-eighth  of  an  inch  in  thickness  was  left,  which 
was  easily  scraped  off,  and  under  this  the  mortar  was  in  good 
condition. 

Many  mechanical  devices  are  employed  both  for  the  mixing 
of  cement  mortar  and  the  conveying  of  mortar  and  stones  to 
the  work,  and  for  laying  the  same.  Descriptions  of  these,  how- 
ever, are  to  be  found  in  special  works  on  the  subject.  The 
chief  object  of  mechanical  mixers  is  thoroughly  to  incorporate 
the  dry  materials  so  as  to  bring  them  into  intimate  contact.  Of 
the  mechanical  conveyors  the  more  common  are  bucket  eleva- 
tors and  inclined  tramways.  Perhaps  the  most  useful  for  the 
construction  of  dams,  which  because  of  their  location  are  usually 
inaccessible,  is  the  overhead  cableway,  by  which  materials  are 
conveyed  from  the  sidehills  and  delivered  to  any  point  on  the 
dam.  One  of  the  most  notable  of  such  cableways  was  that 
used  in  the  construction  of  the  Colorado  River  dam.  This  cable 
was  suspended  on  two  towers,  the  higher  of  which  was  about 
70  feet  tall  and  was  situated  at  a  point  65  feet  above  the  crest 
of  the  dam.  The  main  cable  was  2\  inches  in  diameter  and 
1850  feet  long,  being  1350  feet  between  points  of  support,  and 
on  this  cable  the  carriage  and  its  operating  cables  were  supported. 
On  the  new  Croton  dam  two  steel  towers,  each  25  by  50  feet  in 
plan,  were  used.  In  each  corner  was  a  bull- wheel  derrick  pro- 
vided with  a  separate  driving  engine,  and  each  tower  was  50  feet 
in  height.  On  the  McCall's  Ferry  dam  steel  goose-neck  shaped 
travelling  cranes,  running  on  tracks  on  a  temporary  dam,  were 
used  for  handling  concrete  and  forms  (Fig.  158). 

Various  methods  are  employed  to  preserve  the  batter  lines 
of  a  masonry  dam  during  construction.  On  the  Bhatgur  dam 
this  was  done  by  means  of  large  wooden  forms  constructed  to 
28 


434  MASONRY    DAMS 

scale  from  drawings  and  set  and  tested  by  transit  instruments. 
These  forms  gave  the  masons  outlines  which  they  had  no  diffi- 
culty in  following.  On  the  Sodom  dam  the  true  batter-points 
were  established  for  each  course  of  the  facing  stone  at  every 
twenty  feet  of  the  length  of  the  dam  by  the  use  of  instruments. 
These  batter-points  were  cut  in  the  stone  and  the  foreman  re- 
quired to  work  to  them  for  each  succeeding  course,  and  at  change 
of  batter  short  profiles  fifty  feet  apart  were  set  out  by  the  en- 
gineers to  insure  the  correct  laying  of  the  first  course  at  the  new 
rate  of  batter.  At  McCall's  Ferry  dam  the  forms  consisted  of 
interchangeable  steel  frames  filled  with  wooden  box  lagging  to 
conform  to  the  surface  of  the  dam  (Fig.  158). 

At  Cross  River  dam  of  the  Croton  watershed  and  the  great 
Olive  Bridge  dam  on  Esopus  creek,  in  the  Catskills,  N.  Y.,  the 
batter  lines  of  the  face  are  secured  by  the  use  of  moulded  concrete 
blocks  for  the  faces  of  these  dams.  These  blocks  are  moulded 
in  wooden  forms  provided  with  steel  face  plates  to  insure  smooth- 
ness. They  are  in  headers  and  stretchers  with  interlocking  grooves 
for  bonding,  and  weigh  several  tons  each.  The  concrete  used 
is  i  :  2^  to  4! ,  and  the  mortar  used  for  setting  them  is  i  :  2^,  that 
for  pointing  being  i  :  i. 

338.  Waterproofing  Materials. — It  is  frequently  necessary  to 
line  the  inner  slopes  of  earth  embankments  or  loose-rock  or 
masonry  dams,  and  the  entire  inner  surfaces  of  small  artificial 
storage  reservoirs  such  as  are  used  in  storing  the  discharge  for  a 
day  or  two,  either  of  sewage  or  artesian  water.  It  is  common  to 
use  such  small  distributary  reservoirs  in  connection  with  pumped 
water,  especially  where  pumped  by  wind-mills,  or  for  water  which 
is  to  be  furnished  through  pipes  for  subirrigation. 

Linings  for  large  storage  dams  are  applied  with  the  object  of 
preventing  leakage  which  may  endanger  their  integrity,  or  for 
the  purpose  of  preventing  loss  of  water  as  in  the  case  of  a  loose- 
rock  dam.  Some  of  the  modes  of  making  loose-rock  dams  im- 
pervious have  been  described  in  Arts.  307  to  313.  Several  earth 
dams  with  masonry  cores,  and  gravity  masonry  dams,  have  had 
one  or  more  coatings  of  rich  cement  wash  or  natural  bitumen 
applied  somewhat  like  whitewash  or  as  a  thick  paint  to  their  inner 


WATER-PROOFING    MATERIALS  435 

surfaces  to  make  them  less  pervious.  This  has  proved  effective 
in  preventing  sweating  on  the  outer  surfaces  of  the  dams  or  core- 
walls.  The  only  successful  way  to  make  a  masonry  dam  or 
core-wall  waterproof  is  to  make  the  concrete  or  mortar  rich  in 
cement,  at  least  for  a  few  inches  on  the  face,  and  to  mix  and 
lay  it  relatively  wet  and  to  tamp  it  thoroughly. 

One  of  the  most  impervious  linings  for  earth  embankments  is 
asphaltum.  Its  toughness  and  flexibility  enable  it  to  conform 
without  rupture  to  slight  cracks  and  settlements  of  the  underlying 
material,  thus  indicating  where  repairs  may  be  necessary,  while 
such  repairs  may  be  easily  made  in  the  asphaltum.  The  bottoms 
of  earth  distributary  reservoirs,  the  inner  slopes  of  a  number  of 
earth  embankments  in  California  and  Colorado,  and  the  bottoms 
and  sides  of  earth  canals  and  tunnels  have  been  lined  with  this 
substance,  which  has  remained  in  satisfactory  condition,  always 
easy  to  repair,  for  a  number  of  years,  and  experience  shows  that 
where  properly  applied  such  linings  have  proven  successful  under 
the  most  trying  conditions. 

A  number  of  methods  have  been  devised  for  making  the 
asphaltum  adhere  to  the  surface  beneath,  and  thus  prevent 
slipping  or  crawling  in  hot  weather.  One  of  these  is  by  an- 
choring heavy  burlap  at  the  top  of  the  slope,  stretching  it  tight 
upon  and  pressing  it  into  the  first  coat  of  asphalt.  Upon  this 
a  second  coat  of  asphalt  is  spread.  Such  application  of  burlap 
to  the  Linda  Vista  Reservoir  in  Oakland,  California,  which  is 
35  feet  deep  with  slopes  of  i  on  i,  prevented  the  creeping  of  the 
asphaltum  for  a  number  of  years.  An  equally  successful  mode 
of  fastening  the  asphaltum  is  by  the  use  of  anchor  spikes  cut  from 
strap  iron  about  an  inch  wide  and  6  to  8  inches  long,  which  are 
driven  through  the  asphalt  into  the  banks,  and  over  this  a  second 
coating  of  asphalt  is  applied. 

An  interesting  example  of  the  use  of  asphaltum  for  lining 
dams  is  the  case  of  the  two  West  Ashland  Avenue  reservoirs  in 
Denver,  Colorado,  on  which  this  lining  was  applied  by  Mr.  J.  D. 
Schuyler.  The  maximum  depth  of  one  of  these  reservoirs  is  32 
feet,  with  side  slopes  of  i  on  i  J.  Beginning  at  the  bottom  of  the 
slopes,  the  asphaltum  was  laid  in  horizontal  strips  about  10  feet 


436  MASONRY    DAMS 

wide  with  an  average  thickness  of  if  inches,  and  was  spread  with 
hot  rakes  and  tamped  with  hot  square  tampers  and  ironed  with 
heavy  hot  smoothing-irons  much  as  is  the  asphaltum  used  in  street 
pavements.  While  this  sheet  of  asphalt  was  warm,  strap-iron 
anchor  spikes  i  inch  wide,  J-inch  thick,  and  7  to  8  inches  long 
were  driven  through  the  asphaltum  into  the  bank  in  rows  i  foot 
apart  and  i  foot  between  centers  in  the  row,  every  other  row  being 
flush  with  the  concrete,  the  alternate  rows  being  allowed  to  project 
for  the  support  of  scantling  on  which  the  workmen  stood.  When 
the  final  coat  was  applied  the  projecting  spikes  were  driven  flush, 
and  all  painted  over  with  bitumen. 

The  asphaltum  used  on  these  reservoirs  consisted  of  78% 
La  Petra  asphalt  with  22  %  of  Las  Conchas  flux  from  the  Lower 
California  coast.  This  was  boiled  in  open  kettles  for  twelve 
hours  at  a  temperature  a  little  over  300°  and  frequently  stirred; 
20%  by  weight  of  this  was  mixed  with  80%  of  sand  previously 
heated  to  the  same  temperature.  The  weight  of  this  mixture 
after  being  applied  was  about  127  pounds  per  cubic  foot.  Upon 
this  lining  was  applied  a  second  or  paint  coat  of  pure  Trinidad 
asphaltum  fluxed  with  residuum  oil  and  poured  on  hot  from 
buckets,  and  ironed  over  with  cherry-red-hot  irons.  A  more 
satisfactory  cohesion  was  gotten  between  the  two  coats  by  apply- 
ing the  second  quickly  after  the  first  was  laid  and  while  it  was  still 
warm  and  clean,  the  thickness  of  this  second  coat  being  from  J 
to  \  of  an  inch.  The  cost  of  this  lining  was  about  1 5  cents  per 
square  foot. 

An  asphaltum-concrete  lining  was  used  by  Mr.  R.  B.  Stanton 
in  the  construction  of  a  small  placer-mining  dam  in  an  inaccessible 
portion  of  the  mountains  of  Southern  California,  in  which  asphal- 
tum was  used  as  a  mortar  or  binding  material  with  broken  stone. 
The  stone  was  in  sizes  of  two  inches  and  under,  all  the  fine  material 
and  dust  being  used  so  as  to  form  a  nearly  perfect  concrete.  The 
rock  was  heated  and  mixed  in  a  pan,  and  a  hot  paste  composed 
of  four  parts  of  California  refined  asphaltum  and  one  part  crude 
petroleum  was  boiled  in  another  pan,  poured  over  the  hat  rock, 
and  well  mixed  with  shovels  and  hoes.  This  concrete  was  put  on 
in  layers  four  inches  in  thickness,  in  horizontal  strips  four  to  six 


SUBMERGED   DAMS  437 

feet  wide,  and  where  the  strips  joined  the  old  edge  was  coated  with 
hot  paste.  Over  the  whole  a  second  coating  of  hot  asphaltum 
paste,  mixed  in  the  same  proportions  and  boiled  for  a  much  longer 
time,  was  applied,  which  when  cool  was  hard  and  brittle  like  glass, 
yet  tough  and  elastic  when  warm.  This  paste  was  applied  and 
ironed  down  to  a  thickness  not  exceeding  one-eighth  of  an  inch. 
This  lining  stood  for  several  years  without  showing  a  single 
crack.  In  one  place  the  bank  settled  6  inches  under  a  strip 
4  feet  wide  and  the  lining  followed  the  settlement  without  break, 
and  though  applied  on  a  slope  of  i  J  on  i  it  has  shown  no  tendency 
to  creep,  which  is  one  of  the  great  objections  to  a  lining  composed 
of  asphaltum  and  sand. 

339.  Submerged  Dams. — In  a  few  instances  submerged 
dams  have  been  constructed  for  the  purpose  of  stopping  the 
underground  or  underflow  water  in  the  beds  of  streams.  This 
has  been  resorted  to  particularly  in  a  few  streams  in  the  moun- 
tains of  Colorado  and  California,  where  the  surface  flow  is  large, 
but  as  the  streams  reach  the  platins  the  water  sinks  and  disap- 
pears. Its  downward  course  then  is  stopped  by  some  imper- 
vious bed  of  clay  or  rock,  and  there  is  created  practically  a  slow- 
moving  river  under  a  bed  of  deep  gravel.  This  can  be  brought 
to  the  surface  by  sinking  a  dam  entirely  across  the  stream  bed 
to  the  impervious  substratum,  when  the  water  will  be  raised, 
forming  an  underground  reservoir;  or  a  serious  of  cribs  may  be 
built  on  the  impervious  stratum  under  the  gravels,  and  these 
will  catch  the  water  and  lead  it  off,  whence  it  may  be  removed 
by  an  open  cut  or  by  pumping  (Art.  119). 

The  former  method  is  employed  on  the  San  Fernando  Land 
and  Water  Company's  property  on  Pacoima  Creek  in  Califor- 
nia. At  the  site  of  the  dam  the  sandstone  canyon  walls  are  about 
800  feet  apart  and  the  bed-rock  about  45  feet  below  the  surface 
of  the  gravel  bed  of  the  stream.  Through  this  a  trench  was 
excavated,  in  which  a  cobble-stone  and  Portland-cement  masonry 
wall  was  built  up,  its  bed  width  being  about  3  feet  and  its  top 
width  2  feet,  its  greatest  depth  being  53  feet  and  rising  to  a  height 
of  from  2  to  3  feet  above  the  stream  bed  (Fig.  159).  On  the 
line  of  this  wall  are  two  large  gathering  wells,  and  on  its  upper 


438 


MASONRY   DAMS 


face  pipes  are  laid  in  open  sections,  so  that  the  seepage  water 
caught  by  the  dam  might  enter  these  and  be  led  through  them 
into  the  wells,  from  which  it  is  drawn  off  for  purposes  of  irriga- 
tion. Above  the  dam  the  stream  bed  consists  of  several  hundred 
acres  of  gravel  12  to  20  feet  in  depth,  which  forms  a  natural 
storage  reservoir  of  1200  to  1500  acre-feet  capacity  (Arts.  118  and 
119). 

A  somewhat  similar  submerged  dam  is  in  operation  at  King- 
man,  Ariz.,  for  providing  a  small  supply  to  the  town  and  railway. 
A  masonry  wall  173  feet  long  on  top,  6  feet  wide  at  base,  and 


FlG.  159. — View  of  San  Fernando  Submerged  Dam. 

2  feet  wide  on  top  is  built  on  bed-rock  across  and  through  the 
gravel  bed  of  Railroad  canyon.  A  6-inch  cast-iron  outlet  pipe 
through  the  dam,  12  feet  below  its  crest,  which  is  below  the  level 
of  the  canyon  bed,  leads  into  an  8-inch  standpipe  perforated 
with  f-inch  holes  placed  ^  inch  apart.  In  this  is  collected  the 
water  which  gathers  behind  the  dam  to  the  full  height  of  its  crest* 
340.  Construction  in  Flowing  Streams. — In  building  any 
variety  of  dam  across  a  flowing  stream  the  expense  of  construe- 


CONSTRUCTION    IN    FLOWING    STREAMS  439 

tion  is  considerably  increased  by  the  necessity  of  handling  the 
flowing  water  and  keeping  it  away  from  the  work  of  construction. 
Several  methods  are  pursued,  depending  largely  upon  the  dis- 
charge of  the  stream.  If  this  is  small,  one  of  the  simplest  methods 
is  to  build  an  under  or  scouring  sluice  in  the  dam  and  construct 
this  portion  of  the  work  first,  so  that  the  water  may  be  permitted  to 
flow  off  through  it  while  the  remainder  of  the  work  is  being  built. 
If  the  stream  is  subject  to  violent  floods  or  its  discharge  is  too 
large  to  be  conveniently  handled  in  this  manner,  wasteways  at 
varying  heights  may  be  left  in  the  crest  of  the  dam  over  which 
the  floods  may  fall.  It  is  frequently  necessary  to  build  a  tem- 
porary dam  above  the  main  structure  with  a  view  to  retaining 
the  water  until  the  latter  is  completed;  or  a  temporary  channel 
may  be  built  for  the  stream  around  the  dam,  and  through  this 
the  water  may  be  carried  off.  In  the  great  Tansa  and  Bhatgur 
dams  in  India,  where  the  floods  discharged  were  very  large,  a 
portion  of  the  masonry  adjacent  to  either  abutment  was  main- 
tained at  a  lower  height  than  the  rest  in  order  that  the  floods 
might  flow  over  it  as  over  a  wasteway. 

In  commencing  the  construction  of  a  dam  where  flowing 
water  has  to  be  controlled,  if  the  discharge  is  not  too  great  the 
stream  may  be  diverted  temporarily  while  the  main  portion  of 
the  dam  is  being  built  as  in  the  new  Croton  dam;  or  if  under- 
sluices  are  to  be  provided  for  the  discharge  of  the  water,  these 
should  be  built  first,  the  stream  being  passed  to  one  side  during 
their  construction,  after  which  it  may  be  turned  back  through 
them,  and  the  remainder  of  the  structure  carried  up,  as  in  the 
Roosevelt  dam.  If  no  undersluices  are  to  be  constructed,  pump- 
ing may  be  resorted  to  if  a  temporary  channel  cannot  be  provided, 
though  this  method  is  not  advisable  and  should  rarely  be  resorted 
to.  In  founding  a  dam  in  quicksand  two  or  three  methods  may 
be  employed.  Pneumatic  caissons  may  be  sunk,  and  the  founda- 
tion built  in  these  as  would  be  done  for  a  bridge  pier;  or  if  the 
sand  is  comparatively  dry  and  semi-fluid,  it  may  be  frozen  by  the 
Poetsch  process,  and  the  excavation  for  the  foundation  can  then 
be  made  within  the  frozen  walls;  or  interlocking  steel  sheet  pil- 
ing may  be  driven  through  the  quicksand. 


440  MASONRY   DAMS 

341.  Specifications  and  Contracts. — There  are  many  trivial 
details  of  construction  which  must  be  considered  by  the  engineer 
in  designing  earth,  crib,  and  masonry  dams.     It  is  customary 
to  have  such  structures  built  by  contract,  and  for  this  purpose 
careful  specifications  are  drawn,  detailing  the  character  of  material 
and  construction.     For  those  who  are  unfamiliar  with  such  forms 
of  specifications,  such  books  on  the  subject  of  specifications  and 
contracts  as  those  of  Gould  and  Haupt  can  be  purchased;    or 
specifications  which  have  been  used  by  other  engineers  can  be 
obtained  through  them.     An  excellent  example  of  modern  speci- 
fications are  those  used  by  the  Reclamation  Service  and  repro- 
duced in  Art.  421. 

The  usual  form  of  specification  opens  with  a  general  de- 
scription of  the  work  and  its  location,  a  statement  of  the  methods 
and  appliances  to  be  used  in  construction,  a  description  of  the 
protective  work,  highways,  bridges,  and  diverting  works,  as 
well  as  pumping  plant  and  other  temporary  work  to  be  employed 
during  construction.  For  earth  dams  the  specifications  then 
go  into  a  description  of  the  soil  to  be  used,  and  where  it  is  to  be 
obtained;  the  depth  of  excavation  and  its  character,  and  the 
method  of  retaining  it;  a  description  of  the  refilling  of  excava- 
tions and  the  building  of  embankments;  and  the  question  of 
sodding  and  paving  or  revetting  the  embankments. 

If  the  dam  is  to  be  of  timber  or  loose  rock,  a  description  of 
the  timberwork  and  cribwork  is  given,  and  the  character  of 
the  rock  excavation  and  explosives  to  be  employed  is  entered 
into.  If  of  masonry,  the  matter  of  excavation  for  foundation, 
measurement  and  disposal  of  the  material  removed,  and  method 
of  stepping  the  foundation  are  first  considered.  Then  the  hy- 
draulic masonry  is  described,  the  cement  and  its  tests,  the  pro- 
portions used  in  mixing  mortar  and  concrete,  the  character  of 
the  brickwork  and  of  the  stone  masonry,  whether  of  dry  rubble, 
rubble  masonry,  range-rubble  facing,  or  cut  stone.  In  addition 
to  these  there  is  usually  some  ironwork  connected  with  the  super- 
structure and  gate-houses. 

342.  Examples  of  Masonry  Dams. — In  Table  XXIII  are  given 
the  general  dimensions  of  several  of  the  largest  masonry  dams 


EXAMPLES    OF   MASONRY   DAMS 


441 


which  have  been  built.  An  account  of  the  construction  of  ma- 
sonry dams  would  be  incomplete  without  a  few  examples  of  the 
larger  and  more  typical  of  the  modern  ones,  and  accordingly  brief 
descriptions  and  illustrations  of  some  of  these  are  given  here. 
These  are  divided  for  convenience  into  two  general  classes:  i, 


45.9 


49.08 


FIG.  1 60. — Cross-section  of  Furens  Dam,  France. 

those  which  act  as  retaining-walls  for  the  water  and  over  which 
the  latter  is  not  expected  to  flow;  and,  2,  those  which  act  both  as 
retaining-walls  and  overflow  weirs.  The  older  and  less  typical 
forms  of  dams,  such  as  those  built  in  Spain  in  earlier  days,  and  a 
few  of  those  built  in  France  and  elsewhere,  do  not  require  de- 


442 


MASONRY  DAMS 


scription  here,  as  no  such  works  are  likely  to  be  designed  in  the 
future.  For  those  who  are  interested  in  their  study,  descriptions 
and  cross-sections  of  these  can  be  found  in  Wegmann's  "Design 
and  Construction  of  Masonry  Dams,"  "Krantz's  "  Reservoir 
Walls,"  Schuyler's  " Reservoirs  for  Irrigation,"  or  in  the  twelfth> 


4.00     J 


T  71 


4100 


FIG.  161. — Cross-section  of  Gran  Cheurfas  Dam,  Algiers. 

thirteenth,  and  eighteenth  Annual  Reports  of  the  U.S.  Geological 
Survey. 

343.  Furens  Dam,  France. — This  is  one  of  the  largest  and 
first  of  the  great  dams  built  according  to  modern  formulas 
(Fig.  1 60).  It  is  170.6  feet  in  maximum  height  above  bed-rock, 


GRAN    CHEURFAS    DAM,    ALGIERS 


443 


the  maximum  depth  of  water  being  164  feet;  its  thickness  at 
top  9.9  feet,  and  at  base  161  feet.  The  maximum  pressure  on 
the  masonry  is  6.82  tons  per  square  foot,  while  its  total  length  is 
328  feet  on  top.  In  plan  it  is  curved  with  a  radius  of  828.4  feet> 
and  it  is  built  entirely  of  rubble  masonry,  the  facings  being  of  the 
same  material.  The  top  of  the  dam  is  finished  off  as  a  roadway 


3 


406'  Flood  Level 


'-  4  -LV  -  A  405'  Full  supply 


Weight  of  Masonry,  150  Ibs.  per  sq.  ft. 


Note.    Pressures  reservoir-empty,  in  Ibs.  per  sq.  inch. 
FIG.  162. — Cross-section  of  Tansa  Dam,  India. 

9.8  feet  wide,  and  this  is  protected  by  two  parapets,  one  on  either 
side,  each  1.6  feet  in  height. 

344-  Gran  Cheurfas  Dam,  Algiers.— This  dam  (Fig.  161) 
was  built  in  1882,  and  has  a  total  height  above  its  foundation 
of  98.4  feet.  Its  width  at  top  is  13.1  feet,  at  the  base  72.2  feet, 
and  its  top  length  is  508.4  feet.  It  is  built  practically  in  two 


444  MASONRY  DAMS 

parts,  the  first  consisting  of  a  trapezoidal-shaped  foundation 
mass  of  rubble,  on  which  is  built  the  dam,  the  upper  and  lower 
surfaces  of  which  are  parabolic.  The  depth  of  water  which 
this  dam  will  hold  is  132.2  feet,  and  the  maximum  pressure  on 
the  masonry  within  it  is  6.14  tons  per  square  foot.  In  plan  it 
is  straight. 

345.  Tansa  Dam,  India. — This  great  dam  is  built  through- 
out of  uncoursed  rubble  masonry.     It  is  designed  to  have  a 
total  height  of  133  feet,  though  it  has  as  yet  been  completed 
only  to  a  height  of  118  feet  (Fig.  162).     At  this  height  its  max- 
imum top  width  is  15.2  feet,  while  its  maximum  width  at  base 
is  96.5  feet.     Its  total  length  on  top  is  9350  feet,  while  in  plan 
it  is  built  in  two  tangents,  the  apex  pointing  up-stream.     Near 
the  south  end  is  built  a  wasteway  1800  feet  in  length,  its  crest 
being  3  feet  below  that  of  the  dam.     This  wasteway  is  built  in 
a  portion  of  the  dam  where  its  height  fe  but  a  few  feet,  and  it 
discharges  back  directly  into  the  river  channel  below  the  toe 
of  the  structure.     Near  the  base  of  the  dam  is  a  large  outlet 
tunnel,  which  discharges  into  the  conduit  which  carries  the  water 
to  Bombay  for  the  supply  of  that  city. 

346.  Bhatgur  Dam,  India.— This  dam   (PL    XXV)   is  4067 
feet  in  length,  and  is  constructed  of  the  best  uncoursed  rubble 
masonary  in  cement,  excepting  in  the  upper  central  portion,  where 
the  pressure  is  less  than  60  Ibs.  per  square  inch.     There  it  is  of 
concrete  with  blocks  of  rubble  imbedded  in  it.     On  the  faces  the 
dressed  rubble  is  laid  up  in  courses.     It  is  127  feet  in  height, 
74  feet  in  width  at  the  base,  and  12  feet  wide  on  top  (Fig.  163). 
When  full  the  pressure  on  the  lower  toe  is  5.8  tons  per  square 
foot,  and  -when  empty  the  pressure  at  the  upper  toe  is  6.7  tons 
per  square  foot.     In  plan  the  dam  curves  irregularly  across  the 
valley,  following  an  outcrop  of  rock.     Portions  of  either  end 
of  the  dam,  where  it  is  not  high,  are  left  8  feet  lower  than  the 
remainder  so  as  to  act  as  wasteways.     The  total  length  of  these 
waste  ways  is  810  feet,  and  they  are  arched  over  in  such  manner 
as  to  leave  a  roadway  across  their  tops.     Below  the  dam  and 
jutting  from  it  are  masonry  walls  which  lead  the  waste  water 
off  in  such  manner  that  it  flows  clear  of  the  foot  of  the  dam  and 


446 


MASONRY   DAMS 


passes  off  through  separate  channels  to  the  main  stream  below. 
For  the  purpose  of  scouring  silt  which  may  be  deposited  in  the 
reservoir,  fifteen  undersluices  are  constructed  near  the  center 


3&&tf3-&i  !&&&•££•&&  SK*»«?K  t^ 


JV^P^fc 


-' 


FIG.  163. — Cross-section  of  Bhatgur  Dam,  India. 

of  the  dam,  at  its  deepest  part.  These  are  placed  17  feet  apart 
and  are  4  by  8  feet  in  dimensions,  their  sills  being  60  feet  below 
high-water  mark.  Above  these  are  two  other  undersluices  for 


THE  NEW  CROTON  DAM,  NEW  YORK 


447 


discharging  the  water  to  be  used  in  irrigation  when  the  reservoir 
is  full.  One  of  these  is  20  feet  and  the  other  50  feet  above  the 
main  row  of  undersluices. 

347.  New  Croton  Dam,  New  York. — This  consists  of  a  high 
masonry  darn  for  2260  feet,  thence  to  the  left  bank  the  structure 
consists  of  a  masonry  overfall  weir  of  heavy  cross-section  and 


FIG.  164. — Cross-section  of  Masonry  Dam,  New  Croton  Dam,  Cornell's. 

1020  feet  in  length  on  the  crest.     The  capacity  of  the  reservoir 
is  92,000  acre-feet. 

The  main  dam  has  an  extreme  height  of  297  feet  above  its 
foundation  and  is  166  feet  in  height  above  the  river-bed.  The 
crest  of  the  dam  is  16  feet  above  the  high- water  level  or  crest  of 
the  overfall  weir.  Its  extreme  width  at  base  is  185  feet  and  at  its 
top  1 8  feet,  surmounted  by  a  4-foot  coping.  So  much  of  this 
structure  as  was  built  prior  to  1904  is  of  the  best  rubble-stone 
masonry  laid  in  cement  mortar  and  faced  above  the  ground  sur- 


448 


MASONRY   DAMS 


face  with  coursed  stones  set  in  Portland  cement.  That  built  since 
is  of  cyclopean  rubble  set  in  concrete,  faced  with  rubble  masonry. 
In  plan  the  dam  is  straight  to  the  masonry  overfall  weir,  which 
curves  up-stream  nearly  at  right  angles  to  the  main  structure. 
The  water  falling  over  this  weir  spills  into  an  artificial  channel 
excavated  in  the  hillside  and  emptying  into  the  main  channel 
below  the  toe  of  the  dam.  The  extreme  height  of  the  weir  is  154 
feet,  and  its  extreme  width  at  base  195  feet.  It  has  a  very  slight 
batter  on  the  up-stream  side,  while  its  lower  side  has  a  slightly 
ogee-shaped  curve  broken  by  25  steps  varying  from  2  to  10  feet  in 


FIG.  165. — Cross-section  of  Overfall  Weir,  New  Croton  Dam,  Cornell's. 

height.     This  weir  is  constructed,  like  the  dam,  of  an  uncoursed 
rubble  masonry  interior  and  coursed  faces  (Fig.  165). 

348.  Periar  Dam,  India. — This  dam,  which  is  constructed 
with  a  concrete  hearting,  faced  on  either  side  by  rubble  masonry 
from  6  to  20  feet  in  thickness,  is  1480  feet  long  on  top,  has  a 
maximum  height  of  173  feet  above  bed-rock  and  155  feet  above 
the  river-bed  (Fig.  166).  Its  crest  is  surmounted  by  a  parapet 
5  feet  in  height,  the  maximum  depth  of  water  which  the  dam  will 
hold  being  160  feet,  and  its  width  at  base  138  feet  9  inches,  its  top 
width  being  12  feet.  At  the  right  end  is  a  wasteway  built  in  solid 


BEETALOO  DAM,  SOUTH  AUSTRALIA 


449 


rock,  forming  the  abutment  of  the  dam  and  separated  from  it,  its 
length  being  420  feet.  At  the  left  end  is  an  earth  embankment 
250  feet  long  and  reaching  to  an  elevation  of  170  feet.  The 
maximum  capacity  of  the  reservoir  will  be  306,000  acre-feet,  its 
available  capacity  being  157,000  acre-feet. 

349.  Beetaloo  Dam,  South  Australia. — This  structure   (Fig. 


Roikf 
Scale.  1  inch  =50  fee* 

FIG.  1 66. — Cross-section  of  Periar  Dam,  India. 

167)  is  no  feet  in  maximum  height,  no  feet  wide  at  the  base, 
and  14  feet  wide  on  top.  Its  length  on  top  is  580  feet,  and  it 
is  curved  in  plan,  the  convex  side  facing  up-stream.  It  is  con- 
structed throughout  of  concrete,  and  in  one  end  of  the  dam  is 
built  a  set  of  three  wasteways,  their  total  length  being  200  feet, 
with  their  crests  5  feet  below  that  of  the  main  structure.  These 

20 


45° 


MASONRY    DAMS 


wast cw ays  are  separated  by  masonry  walls,  which  lead  the  flood 
waters  back  into  the  river  below  and  clear  of  the  structure. 

350.  Remscheid  Dam,  Germany. — This  structure  supplies 
the  city  of  Remschied,  and  is  an  excellent  typeof  modern  European 
masonry  structure.  It  is  built  throughout  of  rubble  masonry,  the 
stone  being  a  hard  slate  and  the  mortar  a  hydraulic  lime  some- 
what like  the  pozzolan  of  Italy  and  the  kunkar  of  India.  This 
dam  has  been  finished  for  a  number  of  years  and  shows  no  signs 
of  leakage  or  cracks,  the  upper  face  having  been  heavily  plastered 


•J10  above  S«»  Urcl 


FIG.  167. — Cross-section  of  Beetaloo  Dam,  Australia. 

with  Portland  cement  over  which  twro  coats  of  asphalt  were 
placed.  Outside  of  this  latter  a  brick  wall  ij  to  2\  bricks  thick 
was  carried  up  tight  against  the  asphalt. 

The  dam  is  curved  in  plan,  with  a  radius  of  410  feet.  It  is 
82  feet  high,  49  feet  thick  at  base,  and  13  feet  thick  at  the  crest, 
the  reservoir  capacity  being  1180  acre-feet.  The  masonry  was 
laid  in  curved  instead  of  horizontal  courses  in  such  manner  that 
each  course  is  nearly  perpendicular  to  the  varying  direction  of 
resulting  pressures. 

351.  San  Mateo  Dam,  California. — This  structure  is  built 
throughout  of  concrete,  not  as  a  monolithic  mass,  as  is  the  case 
with  the  Beetaloo  dam,  but,  as  described  in  Article  325,  it  was 
built  up  in  blocks  set  in  place,  the  weight  of  each  being  about  9 
tons.  In  cross-section  this  structure  is  heavier  than  theory  alone 


SAN    MATEO    DAM,    CALIFORNIA 


45 


452  MASONRY    DAMS 

would  require.  As  shown  in  PL  XXVI,  its  maximum  height 
is  170  feet,  its  crest  being  5  feet  above  high-water  mark,  at  which 
level  is  a  wasteway  built  a  short  distance  above  the  north  end 
of  the  dam  and  separated  from  it  by  a  low  ridge.  The  top  width 
of  the  dam  is  25  feet  and  its  width  at  the  bottom  is  176  feet.  Its 
upper  slope  has  a  uniform  batter  of  4  on  i,  while  the  lower  slope, 
beginning  with  a  batter  of  2^  on  i  at  the  top,  curves  to  within  a 
few  feet  of  the  bottom,  where  the  batter  becomes  i  on  i.  In 
plan  this  structure  is  curved  up-stream  with  a  radius  of  637  feet. 
Its  maximum  storage  capacity  is  62,000  acre-feet. 

352.  Sweetwater  Dam,  California. — This  dam  (PL  XXIX) 
is  slighter  in  cross-section  than  theory  would  require,  and  de- 
pends to  a  certain  extent  on  its  curved  plan  for  its  stability.  As 
shown  in  Plates  XXVII  and  XXVIII,  it  is  90  feet  in  maximum 
height,  380  feet  long,  12  feet  wide  on  top  and  46  feet  wide  at 
the  base.  The  radius  of  its  curvature  is  222  feet,  and  as  the 
length  of  the  radius  is  small  and  the  curvature  great,  this  adds 
considerably  to  its  stability.  The  structure  is  built  throughout 
of  large  uncoursed  rubble  masonry,  the  greatest  care  having 
been  used  in  ever}7  detail  of  construction.  At  its  southern  end 
are  a  set  of  seven  escapeways  40  feet  in  aggregate  width,  so 
arranged  that  the  water  issuing  through  them  drops  first  into 
a  series  of  water-cushions,  and  is  then  led  off  by  a  directing  wall 
so  as  to  clear  the  dam.  Near  its  base  is  a  discharge  sluice,  oper- 
ated from  a  water-tower  in  the  reservoir. 

In  1895  tne  dam  was  called  upon  to  withstand  an  extraor- 
dinary flood  during  which  water  to  the  depth  of  22  inches  flowed 
over  its  crest  for  40  hours  without  serious  injury  to  the  structure. 
Afterwards  the  parapet  was  raised  5^  feet,  making  the  greatest 
height  of  the  structure  above  bed-rock  95.5  feet.  The  center 
of  the  parapet  was  lowered  2  feet,  thus  making  an  escape  over 
the  crest  for  a  length  of  200  feet.  The  wasteway  at  the  end  of 
the  dam  was  extended  20  feet  by  adding  four  more  bays  of 
5-feet  width  each.  In  addition  to  other  remedial  measures,  a 
subsidiary  weir  15  feet  high  and  18  inches  thick  was  built  of 
masonry  50  feet  below  the  lower  toe,  and  on  a  concentric  curve 
with  the  main  dam,  to  create  a  water-cushion.  -Finally,  an  un- 


SWEETWATER   DAM,    CALIFORNIA 


453 


454 


MASONRY    DAMS 


45  6 


MASONRY    DAMS 


used  tunnel  in  bed-rock  near  the  wasteway,  8  by  12  feet  in  section, 
was  adapted  for  use  as  an  additional  wasteway  by  laying  in  it 
two  30-inch  and  two  36-inch  iron  pipes  on  a  4  per  cent  grade. 
These  changes  have  increased  the  storage  capacity  of  the  reser- 
voir by  25  per  cent,  or  to  22,566  acre-feet,  and  the  discharge 


FIG.  1 68. — Cross-section  of  Vyrnwy  Dam,  Wales. 

capacity  of  the  combined  wasteway  to  an  amount  believed  to 
be  sufficient  to  pass  the  greatest  possible  flood. 

353.  Vyrnwy  Dam,  Wales. — This  structure  is  peculiar  in 
cross-section  (Fig.  168),  being  unusually  heavy,  and  much  greater 
than  theory  would  demand.  The  reason  for  this  is  that  the 
crest  of  the  whole  dam  acts  as  a  waste  weir,  which  is  surmounted 


ASSUAN    DAM  457 

by  arches  on  which  rests  a  roadway,  and  beneath  these  arches 
the  waste  waters  are  permitted  to  flow.  Its  lower  face  is  given 
an  ogee-shaped  curve,  so 'as  to  reduce  to  a  minimum  the  shock 
of  the  falling  water,  and  there  is  a  depth  of  45  feet  of  back-water 
on  its  toe,  which  forms  a  sort  of  water-cushion.  Its  maximum 
height  is  136  feet,  while  the  greatest  depth  of  water  is  129  feet. 
Its  width  at  base  is  117.7  fect>  and  the  upper  curved  portion 
rests  on  a  massive  pedestal  nearly  rectangular  in  cross-section 
and  43  feet  in  height.  This  dam  is  straight  in  plan,  its  total 
length  on  top  being  1350  feet,  and  it  is  built  throughout  of  large 
cyclopean  rubble,  the  stones  weighing  from  2  to  8  tons  apiece. 

354.  Assuan  Dam  and  Assiout  Weir,  Egypt. — The  former 
of  these  is  the  greatest  masonry  dam  in  existence,  completed  in 
1902,  and  extends  across  the  valley  of  the  Nile  River  and  forms 
a  storage  reservoir  therein  of  about  800,000  acre-feet,  and  is 
estimated  as  capable  of  irrigating  a  large  portion  of  2500  square 
miles  from  the  Ibrahimia  canal,  about  350  miles  lower  down  the 
river  (Art.  131).  This  dam  is  6400  feet  long,  founded  on  granite, 
and  has  a  maximum  height  of  120  feet  in  the  deepest  part  of  the 
foundation  (Fig.  169).  It  is  of  massive  cross-section,  as  the 
floods  of  the  Nile  pass  through,  and  may  pass  over  it.  It  is  80.4 
feet  thick  at  base,  23  feet  wide  on  top,  the  crest  being  9.84  feet 
above  estimated  high  water.  The  batter  of  the  down-stream 
face  is  i  to  i  J.  In  the  structure  are  built  140  undersluices,  each 
6.56  feet  wide  and  23  feet  high,  and  40  sluices  at  a  higher  eleva- 
tion, each  with  one-half  the  area  of  the  lower  series.  These  are 
to  pass  the  floods  of  the  Nile  and  to  scour  the  silt  from  the  reser- 
voir, and  90  of  them  are  designed  to  act  somewhat  as  do  the 
automatic  gates  at  Bhatgur,  India  (Art.  374).  All  of  the  upper 
and  20  of  the  lower  sluices  are  lined  with  cast  iron,  the  remainder 
being  of  cut  stone.  The  piers  between  them  are  16.4  feet  wide 
with  abutment  piers  at  every  tenth  sluice  39.37  feet  wide.  They 
are  expected  to  pass  maximum  floods  of  about  490,000  second - 
feet,  during  which  the  sluices  will  be  open.  The  structure  con- 
tains nearly  1,000,000  cubic  feet  of  masonry. 

At  the  head  of  the  Ibrahimia  canal,  at  Assiout,  a  great  divert- 
ing weir  is  built  across  the  Nile  valley.  This  is  of  rubble  masonry, 


458 


MASONRY    DAMS 


3930  feet  long  and  48  feet  in  maximum  height.     In  it  are  120 
sluices,  each  16.4  feet,  separated  by  piers  6.56  feet  wide. 

355.  Betwa  Dam,  India. — This  structure,  which  has  an  unusu- 
ally heavy  cross-section  (Figs.  170  and  184),  performs  the  functions 
of  a  weir,  the  flood-waters  being  estimated  to  pass  over  the  entire 
crest  to  an  extreme  depth  of  6J  feet.  In  the  extraordinary  flood 


FIG.  169. — Cross-section  Assuan  Dam,  Egypt. 

of  1901  the  depth  on  the  weir  crest  reached  16.4  feet  without  caus- 
ing any  damage  to  the  structure.  The  maximum  discharge  was 
estimated  to  have  been  970,000  second-feet  (Art.  373).  In  plan  it 
is  built  in  three  tangents,  following  the  line  of  an  outcrop  of  rock. 
Its  total  length  is  3296  feet,  its  top  width  being  15.2  feet,  and 
its  maximum  height  about  64  feet.  The  down-stream  face  of 
this  weir  is  supported  by  a  buttress  or  block  of  masonry  15  feet 


BETWA,    DAM,    INDIA 


459 


in  width  and  20  feet  in  height,  while  above  it  the  back-water  in 
the  river  rises  to  an  additional  height  of  about  10  feet,  so  that 
the  flood-waters  will  fall  on  a  water-cushion  of  this  depth  and 
then  on  the  solid  buttress.  This  structure  is  built  throughout 
of  uncoursed  rubble  masonry,  its  faces,  however,  being  coursed 
with  dimension  stone  and  the  coping  being  of  ashlar.  In  the 
river  some  distance  below  its  highest  pbrtion  is  built  a  subsidiary 
or  smaller  weir,  which  backs  the  water  up  against  the  toe  of 


Reservoir 


FIG.  170. — Cross-section  of  Betwa  Dam,  India. 

the  main  weir  in  such  manner  as  to  form  the  water-cushion  on 
which  the  floods  may  fall.  The  extreme  height  of  this  sub- 
sidiary weir  is  18  feet,  and  the  height  of  overfall  from  the  main 
weir  to  the  surface  of  the  water-cushion  is  21 J  feet,  though  in 
time  of  greatest  flood  this  will  be  reduced  to  8  feet.  The  top 
of  the  subsidiary  weir  is  12  feet,  and  its  walls  are  nearly  vertical 
on  the  down-stream  side,  with  a  slope  of  10  to  i  on  the  up-stream 
side. 

The  question  of  increasing  the  storage  capacity  of  the  reser- 
voir dam  having  been  contemplated  for  many  years,  it  was  pushed 


460 


MASONRY    DAMS 


to  completion  in  1901  by  adding  a  series  of  automatic  drop-shutters 
to  the  weir  crest.  As  this  was  of  irregular  cross-section  it  was 
levelled  off  and  the  crest  raised  one  foot  by  adding  rubble  masonry. 
On  this  shutters  6  feet  high  were  placed,  making  the  total  addi- 
tional height  7  feet  (Art.  373)  and  the  added  storage  capacity  of 
the  reservoir  17,500  acre-feet,  equivalent  to  nine  days  full  supply 
of  the  canal,  which  has  a  discharge  of  1000  second-feet.  The 
present  total  capacity  of  the  reservoir  is  therefore  54,300  acre-feet. 
356.  La  Grange  Dam,  California. — This  structure  (Fig.  171) 
is  heavier  in  cross-section  than  theory  alone  would  demand, 
as  it  must  withstand  the  flood-waters  of  the  Tuolumne  River, 
which  passes  over  its  entire  crest  to  a  possible  maximum  depth 


FIG.  171. — Cross-section  of  La  Grange  Dam,  California. 

of  1 6  feet.  About  200  feet  below  the  main  dam  is  built  a  sub- 
sidiary weir,  20  feet  in  height  and  120  feet  in  length,  its  top  width 
being  12  feet.  This  weir  will  back  the  water  up  against  the 
toe  of  the  main  weir  to  a  depth  of  15  feet,  thms  giving  a  water- 
cushion  on  which  the  floods  may  fall.  The  main  weir  is  curved 
in  plan  with  a  radius  of  300  feet;  it  is  320  feet  in  length  on  top, 
90  feet  in  width  at  the  base,  24  feet  in  width  on  top,  and  128  feet 
in  maximum  height,  and  is  built  throughout  of  uncoursed  rubble 
masonry.  The  dam  is  built  for  diversion  purposes  only  (Art. 
147),  hence  its  entire  crest  acts  as  an  overfall  weir.  In  it  are  a 
couple  of  undersluices  which  served  to  pass  water  during  con- 
struction, one  at 'low  water  and  the  other  10  feet  higher,  their 
cross-sections  being  4  feet  wide  by  6  feet  high. 

The  maximum  flood  which  has  passed  over  this  weir  since 


-.. 
— 


462  MASONRY   DAMS 

its  completion  in  1894  was  46,000  second -feet,  the  depth  on  the 
crest  being  12  feet,  while  it  is  estimated  that  it  may  have  to  pass 
floods  of  even  100,000  second -feet. 

357.  Folsom  Dam,  California.— This  structure   (PI.  XXX), 
like  that  just  described,  acts  only  as  a  diversion  weir.     It  is  6gJ 
feet  in  maximum  height  on  the  up-stream  side,  and  98  feet  in 
height  on  the  down-stream  side.     Its  cross-section  is  unusually 
heavy,  as  flood-waters  to  a  depth  of  over  30  feet  are  expected  to 
flow  over  its  crest  (PL  XXXI).     Its  top  width  is  24  feet,  and  its 
extreme  width  at  base  87  feet,  the  toe  terminating  in  a  heavy 
buttress  of  masonry.     Its  total  length  on  the  crest  is  about  520 
feet,  a  large  portion  of  which  consists  of  a  retaining- wall  leading 
to  the  canal  entrance.     One  hundred  and  eighty  feet  in  length 
in  the  center  of  the  main  dam  is  lowered  a  depth  of  6  feet  to  form 
a  wasteway  over  which  the  floods  may  pass,  and  this  wasteway 
is  closed  by  a  single  long  shutter,  consisting  of  a  Pratt  truss 
backed  with  wood,  which  can  be  raised  and  lowered  by  means  of 
hydraulic  presses,  operated  from  a  power-house  near  by.     The 
dam  is  constructed  throughout  of  uncoursed  rubble  masonry. 

358.  Austin  Dam,  Texas. — This  dam  was  built   in   1891-2 
across  the  Colorado  River  for  the  supply  of  water  and  water- 
power  to  the  city  of  Austin,  Texas.     In  1900,  during  a  flood 
which  topped  its  crest  to  a  depth  of  nearly  10  feet,  it  failed  by 
the  sliding  down-stream  intact  of  a  section  500  feet  in  length, 
due-  largely  to  an  insufficient  bonding  of  the  foundation  in  bed- 
rock, which  was  of  a  limestone  easily  leeched  and  seamed.     Its 
interior  was  of  rubble  masonry,  faced  on  both  sides  and  on  top 
with  large  cut  blocks  of  coursed  granite.     It  was  1275  feet  long 
on  top,  1125  feet  of  which  are  constructed  as  an  overfall  waste- 
way,  and  66  feet  in  maximum  height,  its  upper  face  being  vertical. 
The  lower  face  had  an  easy  ogee-shaped  curve  (Fig.  172),  calcu- 
lated to  pass  the  waters  with  such  ease  that  the  erosive  action 
at  the  base  would  be  reduced  to  a  minimum.     The  structure 
was  practically  a  great  overfall  weir,  the  maximum  flood  to  be 
passed  being  estimated  at  250,000  second-feet  from  a  catch- 
ment basin  of  50,000  square  miles. 

The  cross-section  was  heavier  than  theorv  would  demand 


AUSTIN   DAM,    TEXAS 


463 


/! 


CROSS  SECTION  OF  WEIR. 


PLATE  XXXI.— Folsom  Canal  Plan  and  Cross-section  of  Weir. 


464 


MASONRY    DAMS 


if  the  dam  were  built  to  act  as  a  retaining-wall  only.  The  lower 
portion  of  the  down-stream  face  was  curved  with  a  radius  of 
31  feet  tangent  at  the  bottom  to  low-water  surface,  so  as  to  de- 
liver the  floods  away  from  the  toe  and  against  the  back-water 
in  the  river.  The  upper  end  of  the  curve  was  tangent  to  the 
main  slope,  which  has  a  batter  of  3  in  8,  and  ends  on  top  in  a 
curve  of  20  feet  radius.  This  top  curve  was  tangent  to  the  hori- 
zontal crest  line,  which  is  5  feet  wide.  The  total  top  width  was 
1 6  feet,  and  the  maximum  width  at  base  68  feet. 

359.  Overfall   Masonry   Dam,    Spier    Falls,   N.    Y.— This    is 


Scale 


FIG.  172. — Cross-section  of  Austin  Dam. 

probably  the  longest  and  one  of  the  highest  masonry  dams  ever 
built  across  the  channel  of  a  great  river.  It  is  located  on  the 
Hudson  River,  in  New  York,  about  9  miles  above  Glens  Falls, 
and  furnishes  water  for  power,  with  an  8o-foot  head,  to  ten  tur- 
bines, each  capable  of  developing  5000  horse-power.  These 
drive  dynamos  which  feed  50,000  horse-power  of  electricity 
to  Glens  Falls,  Troy,  Saratoga,  Schenectady,  and  Albany,  from 
9  to  42  miles  distant. 

The  foundation  was  laid  with  the  aid  of  great  coffer-dams 
resting  on  a  river-bed  composed  of  masses  of  bowlders,  cemented 
gravel,  and  hardpan.  The  cribwork  was  almost  entirely  covered 
by  the  material  excavated  from  the  dam  site,  which  thus  aided 
as  a  reinforcement  and  was  essential  as  an  aid  in  stopping  leaks. 
The  main,  coffer-dam  was  of  huge  dimensions,  being  250  feet  in 


OVERFALL   MASONRY   DAM,    SPIER    FALLS,    N.Y.          465 

maximum  width  at  base,  80  feet  wide  at  top,  90  feet  high,  and 
600  feet  long  on  top. 

A  portion  of  the  dam  in  the  river  section  is  of  the  usual  gravity 
masonry  section,  as  shown  in  Fig.  173,  the  remainder  is  built  as  a 


Rad.=  81.74- 


FIG.  173. — River  Section,  Spier  Falls  Dam,  New  York. 

spillway  on  the  north  side  of  the  river  and  has  an  admirable  over- 
fall section  (Fig.  174).  This  spillway  was  built  first  and  in  it  four 
archways,  7  by  10  feet,  were  left  as  undersluices  to  carry  the 'river. 

3° 


466 


MASONRY  DAMS 


These  sluices  were  35  feet  above  the  river-bed,  and  were  finally 
closed  with  sliding  gates  and  permanently  filled  with  mason ry. 
The  maximum  height  of  the  overfall  section  is  80  feet  above  the 
river-bed  with  a  width  on  top  of  about  1 7  feet.  The  top  is  curved, 
however,  with  a  radius  of  16  feet,  and  thence  the  down-stream 
curve  is  reversed  to  a  straight  section  having  a  batter  of  .6  foot 
per  foot,  and  this  eases  off  to  a  concave  curve  of  35  feet  radius. 

The  river  section  or  main  dam  has  a  top  width  of  17  feet,  a 
height  above  river-bed  of  90  feet  and  a  maximum  height  above 


FIG.  174. — Overfall  Section,  Spier  Falls  Weir,  New  York. 

foundations  of  152  feet.  Its  maximum  width  at  bottom  is  113  feet 
and  the  cross-section  that  called  for  by  modern  formulae.  Both 
the  main  and  the  spillway  dams  are  founded  on  a  hard-granite 
rock. 

The  material  used  in  the  dam  is  rough  rubble  masonry  of 
all  sizes  of  granite  stones  up  to  some  of  cyclopean  dimensions. 
These  are  set  in  concrete  cement  and  into  the  large  spaces  spalls 
were  rammed.  The  mode  of  construction  of  this  rubble  concrete- 
is  almost  identical  with  that  used  on  the  Bhatgur  dam,  India, 
except  that  the  facing  stones  were  even  less  shaped  and  dressed. 
The  face  stones  in  the  river  section  were  laid  dry  with  their  beds 
inclined  to  the  horizon,  the  joints  being  grouted.  The  face  stones 
of  the  overfall  section  were  brought  from  a  distance  and  were 
carefully  dressed. 

360.  Roosevelt  Dam,  Arizona. — This   structure  creates  the 


PLATE  XXXII.— Plan  of  Rcx>scvelt  Dam,  Arizona.        467 


468  MASONRY   DAMS 

storage  reservoir  of  the  Salt  River  Valley  project.  It  was  built  on 
the  Salt  River  below  its  junction  with  the  Tonto  River,  about  50 
miles  above  Phoenix,  Ariz.,  by  the  United  States  Reclamation  Ser- 
vice, and  stores  about  1,100,000  acre-feet  of  water  in  a  reservoir  20 
miles  long  by  from  i  to  2  miles  wide  up  the  Salt  River  and  about 
16  miles  up  the  Tonto.  Floods  exceeding  4000  second-feet  are 
liable  to  pass  over  the  dam,  and  were  carried  off  during  construc- 
tion through  the  permanent  outlet  tunnel  constructed  in  solid 
rock  under  the  abutments  before  the  structure  was  closed.  The 
dam  has  a  maximum  cross-section  (PL  XXXIII)  270  feet  in 
height  above  the  lowest  point  in  foundation,  the  height  of  spillway 
being  210  feet  above  mean  low  water.  The  roadway,  bordered 
by  a  parapet  along  the  crest,  is  230  feet  above  mean  low  water 
and  1 6  feet  in  width.  The  length  of  the  dam  at  river-bed  is  210 
feet  and  700  feet  along  the  top,  and  its  extreme  width  about  165 
feet  (PL  XXXII).  This  is  one  of  the  highest  masonry  dams  ever 
constructed,  and  contains  about  300,000  cubic  yards  of  masonry. 
The  outlet  tunnel  is  about  400  feet  long,  and  in  it  are  placed  six 
gates  for  sluicing  out  silt  and  regulating  the  flow  of  water  to  be 
drawn  off  (Art.  381).  This  is  discharged  into  Salt  River  down 
which  it  runs  about  50  miles  to  a  diversion  weir,  where  it  is  picked 
up  at  the  Granite  Reef  weir  (Art.  188),  and  distributed  through 
canals  to  the  irrigable  lands  m  the  vicinity  of  Phoenix  and  Mesa, 
Ariz.  The  whole  system  of  dams,  canals,  distributaries,  etc.,  is 
known  as  the  Salt  River  Project,  and  the  storage-water  is  expected 
to  irrigate  nearly  200,000  acres. 

Incidentally  the  power  plant,  built  at  the  foot  of  the  dam 
for  utilizing  the  energy  of  the  water  to  be  drawn  off  to  the  80- 
foot  level,  and  other  power  plants  to  be  erected  along  the  Salt 
River  at  falls,  develop  about  10,000  horse-power,  which  is  electri- 
cally transmitted  to  irrigable  lands  and  utilized  in  pumping  a 
sufficient  amount  of  water  estimated  to  irrigate  50,000  additional 
acres.  The  lands  of  the  Salt  River  valley  contain  at  least  three 
water-bearing  strata;  the  second,  extending  to  a  depth  of  over 
200  feet,  is  already  being  extensively  pumped  and  furnishes  such 
an  abundant  supply  that  no  appreciable  effect  on  the  water-level 
has  yet  been  produced. 


ROOSEVELT   DAM,    ARIZONA 


469 


Water  $urface+2 


' 


El. -30' 


u-io4>^iof"' 

1—10^4—  -  181.04  feet- 

j« 158  feet 

Scale  of  Feet 


0        10        20       30       40        50 

PLATE  XXXIII. — Maximum  Cross-section,  Roosevelt  Dam,  Arizona. 


47°  MASONRY   DAMS 

The  masonry  in  the  dam  is  of  broken-range  cyclopean  rubble, 
made  so  as  to  break  joints  and  be  thoroughly  bonded  in  all 
directions.  Electricity  for  lighting  by  night  and  for  development 
of  power  for  handling  derricks  and  cement  plants,  etc.,  was 
furnished  from  a  power  canal  19  miles  long,  taken  from  the  Salt 
River  above  the  dam,  and  having  a  capacity  of  200  second-feet. 

The  dam  is  built  on  a  curve  having  an  up-stream  radius  of 
about  400  feet,  though  its  cross-section  is  that  required  by  theory, 
and  closely  resembles  that  of  the  new  Croton  dam,  N.  Y.  (Art. 
347).  The  concrete  consists  of  i  part  Portland  cement,  2\  parts 
sand,  including  run  of  crusher  passing  J-inch  screen,  and  4  parts 
of  broken  stone  up  to  and  not  exceeding  2-inch-mesh  screen;  the 
sand  contained  not  more  than  10  per  cent  clay  or  other  foreign 
substance.  The  stones  were  laid  not  nearer  than  2  inches  apart, 
and  weighed  up  to  10  tons  or  greater.  The  upper  100  feet  of  the 
dam  was  reinforced  during  construction  with  railroad  steel  to 
enable  it  to  resist  tensile  strains  due  to  temperature  changes. 
Moreover,  it  was  built  only  when  the  temperature  was  below 
normal,  thus  insuring  compressive  strains  most  of  the  time. 

The  specifications  for  the  construction  of  the  dam,  which  with 
auxiliary  and  diversion  works  is  estimated  to  cost  $3,200,000,  are 
presented  in  Article  420  as  a  fair  sample  of  similar  specifications 
issued  for  the  construction  of  other  work  of  the  Reclamation 
Service. 

361.  Shoshone  Dam,  Wyoming. — This  structure  was  built  by 
the  Reclamation  Service  to  store  water  on  the  Shoshone  River, 
Wyoming.  Thence  the  stored  water  flows  down  the  river  for  a 
number  of  miles  to  the  Corbett  weir  (Art.  187)  which  diverts  it 
through  a  tunnel  to  the  Garland  canal  for  irrigation  in  the  neigh- 
borhood of  Cody. 

The  dam,  which  is  of  cyclopean  rubble,  is  310  feet  high,  200 
feet  long  on  top  and  85  feet  at  bottom.  It  is  curved  up-stream 
with  a  radius  of  150  feet  and  has  a  cross-section  far  lighter  than 
required  by  theory,  being  largely  dependent  for  its  stability  on 
arch  action.  The  up-stream  face  has  a  batter  of  0.15  in  i  and 
the  down-stream  face  0.25  in  i  to  within  60  feet  of  the  bottom 
below  which  the  sides  are  vertical.  The  top  width  is  10  feet  and 


SHOSHONE    DAM,    WYOMING  471 

the  bottom  width  108  feet  (Fig.  075).  The  reservoii  capacity  is 
456,000  acre-feet.  The  foundation  and  walls  are  of  granite, 
of  which  material  the  dam  is  built.  There  is  a  spillway  250  feet 
long  discharging  through  a  tunnel  in  the  hillside. 


5065' 


FIG.   175. — Cross-section  of  Shoshone  Dam,  Wyoming. 


362.  Bear  Valley  and  Zola  Dams. — Two  of  the  most  notable 
curved  dams  are  the  Bear  Valley  dam  in  California  and  the 
Zola  dam  in  France,  the  cross-sections  of  which  arc  unusually 


472 


MASONRY    DAMS 


light,  as  they  depend  chiefly  on  their  curved  plan  for  their  stability. 
The  former  (Fig.  176)  is  but  3.2  feet  in  width  on  top,  and  at  a 
depth  of  48  feet  below  its  crest  its  width  is  but  8.4  feet.  At 

this  point  an  offset  of  2  feet  is 
made  on  each  side,  and  its  width 
thence  increases  to  20  feet  at  its 
base,  which  is  at  a  point  64  feet 
below  its  crest.  The  structure  is 
450  feet  in  length  on  top,  and 
in  plan  it  is  curved  with  a  300- 
foot  radius  (Fig.  177).  It  is  built 
throughout  of  the  best  uncoursed 
rubble  granite  masonry,  and 
depends  almost  wholly  on  its 
curved  plan  and  the  excellence 
of  its  construction  for  its  stabil- 
ity, since  the  lines  of  pressure 
with  the  reservoir  full  fall  from 
13  to  15  feet  outside  of  its  base. 
The  Zola  dam  (Fig.  178)  is  123  feet  in  maximum  height,  19 
feet  in  width  on  top,  and  41.8  feet  in  width  at  the  base.  Its 
length  on  top  is  205  feet,  and  it  is  curved  with  a  radius  of  158 
feet.  Like  the  Bear  Valley  dam,  it  depends  chiefly  on  its  curva- 


FIG.  176. — Cross-section  of  Bear 
Valley  Dam,  California. 


FlG.  177. — Plan  and  Elevation  of  Bear  Valley  Dam,  California. 

ture  and  the  excellence  of  its  construction  for  its  stability.     The 
material  of  which  it  is  built  is  uncoursed  rubble  masonry. 

363.  Upper    Otay    Dam,    California. — This    is    a    masonry 


UPPER    OTAY    DAM.    CALIFORNIA 


473 


structure  of  unusually  light  cross-section,  being  nearly  as  frail 
in  dimensions  as  the  celebrated  Bear  Valley  dam.  It  is  located 
on  the  north  branch  of  Otay  River,  above  Lower  Otay  reservoir 
(Art.  311),  at  a  narrow  gorge  where  there  are  excellent  porphyry 
abutments  the  width  between  which  at  stream-bed  is  but  20  feet. 
The  length  of  the  dam  at  the  top  is  350  feet,  its  maximum  height 
above  bed-rock  is  75  feet,  and  in  plan  it  is  curved  with  a  ladius 


_____  _n  n 


UPPER  OTAY 


SWEETWATER  DAM 


ZOLA  DAM 


FIG.  178. — Sections  of  Arched  Masonry  Dame. 

of  359  feet     (PI.  XXXIV).     The  greatest  width  or  thickness  at 
base  is  but  14  feet,  the  width  on  the  crest  is  4  feet. 

This  dam  was  built  with  great  care,  of  the  best  Portland- 
cement  concrete  masonry,  and  for  its  length  and  height  probably 
ranks  with  any  structure  of  its  kind  in  minimum  section  and  cost. 
Two  tiers  of  steel  plates  were  set  in  the  cement  longitudinally  at 
the  axis  of  the  dam  to  add  strength,  and  i^-inch  railway  cables 
were  laid  above  these  vertically  at  intervals  of  2  feet  and  reach- 
ing within  5  feet  of  the  crest.  It  was  completed  to  its  present 
height  several  years  ago,  but  the  catchment  basin  above  it  is  so 
limited  that  it  has  never  yet  been  filled,  nor  is  it  likely  that  it  ever 
will  be  filled,  from  its  own  drainage  basin.  Therefore  there  is 
little  danger  of  its  being  topped  by  a  flood.  The  storage  capacity 
of  the  reservoir  is  but  2000  acre-feet.  There  is  a  very  limited 
wasteway  at  one  end,  and  in  the  top  or  crest  are  a  number  of 


474  MASONRY    DAMS 

notches  about  4  feet  in  depth  designed  to  waste  before  the  crest 
is  reached. 

364.  Buttressed  and  Arched  Masonry  Walls. — A  dam  has  two 
functions  to  perform;  one,  to  present  an  impervious  barrier  to 
seepage,  through  its  body;  and,  two,  to  withstand  the  pressure 
tending  to  thrust  it  away  or  overturn  it.  The  first  is  effected 
by  the  impervious  nature  of  the  materials  opposing  it,  as  clay 
puddle,  cement  masonry,  wooden  facing,  etc.  The  second  by 
the  weight  or  stability  of  the  mass  of  the  structure. 

Efforts  have  been  made  from  time  to  time  to  procure  imper- 
viousness  by  light  steel  faces,  as  at  Ash  Fork  (Art.  365)  where 
stability  is  secured  by  steel  framing  securely  anchored.  At 
least  three  masonry  dams  have  been  built  with  this  end  in  view 
by  erecting  comparatively  thin  masonry  walls  and  bracing  them 
with  buttresses  or  vertical  arches.  One  of  these  is  the  dam  at 
Lake  Fife,  which  furnishes  the  water-supply  of  Poona,  India. 
This  structure  is  founded  on  sloping  rock  and  is  built  of  un- 
coursed  rubble  masonry.  Its  total  length  is  5136  feet,  of  which 
453  fee^  ac^  as  a  wasteway;  its  maximum  height  above  the 
foundation  being  80  feet.  The  design  of  the  dam  is  crude.  At 
first  it  was  built  14  feet  wide  on  top,  with  straight  slopes  on  either 
side  of  2  on  i  down-stream  and  20  on  i  up-stream.  It  soon  showed 
signs  of  weakness,  and  to  strengthen  it  a  great  earthen  embank- 
ment 1 6  feet  wide  on  top  and  30  feet  high  was  built  against 
its  lower  face.  In  plan  the  dam  is  in  several  tangents,  with  change 
of  top  width  for  each,  and  at  the  points  of  juncture  the  masonry 
wall  is  backed  up  by  heavy  buttresses  of  masonry. 

A  masonry  dam  of  very  unusual  design  is  that  which  closes 
Meer  Allum,  from  which  the  water-supply  of  the  city  of  Hyder- 
abad, India,  is  drawn.  The  structure  is  built  in  the  form  of  a 
large  arch  which  consists  of  twrenty-one  smaller  arches  or  scallops, 
transmitting  the  water  pressure  to  solid -masonry  buttresses.  The 
lake  has  an  area  of  about  9000  acres  and  a  capacity  of  about 
6500  acre-feet.  The  greatest  depth  of  water  is  nearly  50  feet. 
The  catchment  area  of  the  basin  is  hilly  and  undulating  and  fairly 
well  covered  with  jungle.  The  main  feeder  of  the  lake  takes 
its  rise  from  the  river  Esee,  and  is  about  eight  miles  in  length. 


476 


MASONRY   DAMS 


The  dam  is,  roughly,  half  a  mile  in  length,  and  the  twenty-one 
arches  composing  it  range  all  the  way  from  70  to  147  feet  in 
length  of  span.  The  largest  of  these  arches,  which  is  about  the 
center  of  the  dam,  is  shown  in  Fig.  179.  The  dam  is  built 
with  walls  vertical  on  both  faces,  the  down-stream  face  being 
rapidly  stepped  out  near  the  top  so  as  to  attain  the  maximum 


SECTION  A-B 


SECTION  C-D 


FIG.  179.— Meer  Allum  Dam,  India.     Plan  and  Sections  of  One  Arch. 

thickness  of  8  feet,  6  inches  within  a  few  feet.  A  waste  weir  is 
provided  at  one  end  of  the  dam,  but  during  heavy  rains,  when 
the  lake  is  full,  the  water  flows  to  a  depth  of  i  or  2  inches  over 
the  crest  of  the  whole  dam. 

At  Belubula,  New  South  Wales,  is  a  somewhat  similar  struc- 
ture 60  feet  in  height,  431  feet  long,  but  with  six  buttresses  28 
feet  apart  from  center  to  center,  each  being  40  feet  long  and 
from  ;  to  12  feet  thick.  Within  these  brick  arches  were  built 


BUTTRESSED    AND    ARCHED   MASONRY   WALLS 


477 


4  feet  thick  at  bottom  and  ij  feet  at  top,  at  an  angle  of  about 
60  degrees  to  the  horizontal. 

A  unique  buttressed  dam  of  reinforced  concrete  has  been  built 
by  the  Reclamation  Service  to  close  East  Park  reservoir,  Orland 
project,  California.  This  dam,  which  acts  as  a  spillway  in  flood, 


Expansion 


f  Cut  off  wall 
1 18"  Wide,  totw 
carried  well  Into 

SECTION  C  C 
FIG.  1 80.— East  Park  Dam  and  Spillway,  Orland  Project,  California. 

is  but  ii  feet  high  and  consists  of  a  number  of  circular  walls  of 
13^  feet  radius,  convex  up-stream  and  sustained  by  concrete 
buttresses  of  8  ft.  thickness,  sloping  down-stream  with  gradient 
bfijto  i. 

These  walls  (Fig.  180)  are  of  reinforced  concrete  18  inches 


478  MASONRY    DAMS 

thick,  resting  on  a  floor  12  inches  thick,  and  below  the  walls  and 
between  ihe  buttresses  are  subsidiary  walls  2  feet  high  forming 
water-cushions.  Down-stream  is  a  concrete  apron  8  inches 
thick  extending  for  a  distance  of  30  feet. 

365.  Steel  Dam,  Ash  Fork,  Arizona. — This  structure,  built 
wholly  of  metal  and  intended  for  the  impounding  of  water,  was 
built  by  the  Santa  Fe  railway  to  store  water  for  use  of  locomotives 
and  for  city  supply,  and  has  a  capacity  of  no  acre-feet.  A 
similar  dam,  70  feet  high,  built  across  the  Missouri  River,  near 
Helena,  Montana,  recently  failed  during  a  flood. 

The  Ash  Fork  dam  is  184  feet  long  on  top,  and  about  300  feet 
in  total  length,  including  a  short  concrete  abutment  at  each  end. 
Its  greatest  height  is  46  feet.  Structurally  it  consists  of  a  series 
of  triangular  steel  bents  or  frames,  resting  on  concrete  founda- 
tions and  carrying  steel  face-plates  on  the  inclined  or  up-stream 
face  of  the  bents.  The  foundations  of  the  steel  bents  are  of 
Portland-cement  concrete  and  the  vertical  posts  rest  on  concrete 
walls  (Fig.  181). 

There  are  24  bents,  each  a  right-angled  triangle,  with  the 
inclined  side  having  a  slope  of  45°,  facing  up-stream,  the  rocky 
bottom  of  the  canyon  forming  the  base.  The  dimensions  of  the 
bents  vary  with  their  height.  The  end  bents  (Nos.  i  to  7  and 
No.  24)  are  12  to  21  feet  in  height,  each  consisting  of  a  vertical 
Z-bar  column  and  an  inclined  I-beam.  Bents  Nos.  8,  9,  22, 
and  23  are  about  33  feet  high.  Each  has  a  vertical  Z-bar  column, 
an  inclined  I-beam,  and  two  inclined  posts  or  columns  built  up 
of  Z-bars,  the  upper  of  these  resting  on  the  same  shoe  or  bedplate 
as  the  vertical  post.  Bents  Nos.  ic,  n,  12,  19,  20,  and  21  are 
33  feet  to  41  feet  10  inches  high.  These  have  but  one  inclined 
post,  which  rests  on  the  same  bedplate  as  the  vertical  post  while 
above  it  are  truss  members. connecting  the  face  member  with  the 
posts.  Bents  Nos.  13  to  18,  inclusive,  are  36  feet  to  41  feet  10 
inches  high,  and  have  two  inclined  posts,  with  truss  members 
above  the  upper  post.  In  all  of  them  the  face  is  composed  of 
a  2O-in.  65-lb.  I-beam,  reinforced  on  the  underside  by  a  plate  J 
inch  thick  and  18  inches  wide.  The  vertical  and  inclined  posts 
are  all  composed  of  four  Z-bars  and  a  web-plate.  The  bents  are 


STEEL    DAM,    ASH    FORK,    ARIZONA 


479 


connected  by  four  sets  of  transverse  diagonal  bracing  between 
the  vertical  and  inclined  posts.  The  bracing  is  composed  of 
single  or  double  angle-irons,  1X3X3  inches,  the  ends  of  which 
are  riveted  to  connect  ion -plates. 

The  structure  is  composed  of  alternate  rigid  and  loose  panels. 
The  crest  or  apron -plates  which  fit  the  braced  panels  between  the 
bents  are  riveted  to  a  curved  angle,  which  is  riveted  to  the  upper 
end  of  the  curved  plate,  while  in  the  unbraced  panels  this  curved 
angle  merely  bears  on  the  apron-plate.  The  face  of  the  dam 


FIG.  181. — Steel  Dam,  Ash  Fork,  Arizona. 

is  composed  of  steel  plates  -jj  inch  thick  and  8  feet  io§  inches 
wide  and  8  feet  long,  riveted  to  the  outer  flanges  of  the  I-beams 
of  the  bents.  They  are  curved  transversely  to  a  radius  of  7  feet 
6  inches,  forming  a  series  of  gullies  or  channels  down  the  face, 
the  width  of  the  channels  being  7  feet  5  inches  measured  on  the 
chord,  leaving  at  each  side  a  flat  portion  which  rests  on  and  is 
riveted  to  the  I-beams.  There  are  seven  expansion  rivets  at 
intervals  of  about  five  bents,  and  all  joints  exposed  to  water- 
prcssure  are  well  caulked. 

A  weakness  of  the  structure  is  the  failure  to  have  provided 


480  MASONRY    DAMS 

a  wasteway,  the  crest  of  the  structure  being  expected  to  pass 
floods  to  a  depth  of  six  feet.  Moreover,  the  masonry  foundations 
were  not  carried  down  to  impervious  rock,  and  in  consequence 
the  dam  at  first  failed  to  serve  its  purpose,  much  of  the  water 
impounded  being  passed  under  and  around  it  by  s«epage  through 
the  permeable  loose  rock  and  volcanic  cinder  foundation  material. 
Later  concrete  was  used  to  connect  the  steel  facing  with  the  rock 
foundations,  and  this  was  covered  with  asphaltum  and  is  reported 
to  have  greatly  reduced  the  leakage. 


CHAPTER  XVIII 

WASTEWAYS    AND    OUTLET    SLUICES 

366.  Wasteways. — Wasteways,  escapes,  or  spillways  as  they 
are  sometimes  called,  are  an  essential  adjunct  of  every  dam. 
They  are  to  a  reservoir  what  a  safety-valve  is  to  a  steam-engine; 
the  means  of  disposing  of  surplus  waters  due  to  floods  and  pre- 
venting these  from  topping  the  dam  and  possibly  causing  its 
destruction.  Water  should  not  be  permitted  to  flow  over  the 
crest  of  a  masonry  dam  unless  it  has  been  built  in  an  unusually 
substantial  manner  calculated  to  withstand  the  shock  of  its 
overfall.  It  should  never  be  permitted  to  flow  over  the  face 
of  a  loose-rock  or  earth  dam.  The  outer  slope  of  an  earth  dam 
is  its  weakest  part,  and  if  water  is  permitted  to  top  it  it  will 
speedily  cut  it  away  and  cause  a  breach. 

Too  many  of  the  great  floods  which  have  occurred  in  recent 
years  bear  testimony  to  the  necessity  of  constructing  substan- 
tial and  ample  wasteways.  Moreover,  an  ample  wasteway  being 
provided,  the  greatest  care  shoud  be  exercised  to  maintain  it 
always  open  and  ready  for  use,  independent  of  all  undersluices 
and  other  discharge  outlets  which  may  be  closed  by  valves  or 
other  mechanical  means.  To  the  lack  of  one  or  both  of  these 
precautions  was  due  the  destruction  of  the  South  Fork  dam  in 
Pennsylvania  in  1889;  of  the  Walnut  Grove  dam  in  Arizona  in 
the  spring  of  1890,  and  many  other  similar  catastrophes.  Had 
the  wasteway  to  the  South  Fork  dam  been  ample,  as  it  origi- 
nally was,  the  water  would  not  have  flowed  over  the  crest  of  the 
dam  and  have  caused  its  destruction  and  that  of  Johnstown. 
But  the  wasteway  was  barred  by  fish-screens,  and  these  not  only 
obstructed  the  passage  of  the  water  but  caught  floating  timber 
and  logs  brought  down  by  the  flood,  which  so  diminished  the  area 
of  the  spillway  as  to  cause  the  waters  to  top  the  dam.  In  the 
case  of  the  Walnut  Grove  dam  the  area  of  the  wasteway  was  in- 
31  481 


482  WASTEWAYS    AND   OUTLET   SLUICES 

sufficient,  resulting  consequently  in  the  passage  of  much  of  the 
flood-water  over  the  dam  crest  and  in  the  destruction  of  the  work. 

367.  Character  and  Design  of  Wasteways. — In  design- 
ing a  wasteway  for  a  reservoir,  data  relating  to  the  greatest  floods 
likely  to  occur  must  be  sought  for  in  its  catchment  basin,  and 
the  dimensions  of  the  wasteway  must  be  proportioned  for  the 
extraordinary  floods.  The  methods  of  determining  the  great 
floods  and  the  necessity  for  looking  for  signs  of  these  in  the  valleys 
has  already  been  discussed  in  Chapter  IV.  Should  other  reser- 
voirs exist  above  that  under  consideration,  provision  must  be 
made  for  the  discharge  of  their  contents  lest  their  embankments 
give  way;  this  can  only  be  done  by  considering  their  volume 
and  calculating  the  velocity  and  consequent  quantity  which 
will  reach  the  dam  at  any  one  time.  It  would  be  well,  after  having 
ascertained  the  greatest  known  flood  to  be  passed,  to  exceed 
this  as  a  factor  of  safety,  for  almost  every  masonry  dam  has 
at  some  time  been  topped  by  a  flood  greater  than  calculated  for. 

Having  fixed  on  the  area  of  the  wasteway  from  a  knowledge 
of  the  maximum  flood  to  be  discharged,  the  chief  consideration 
to  be  borne  in  mind  is  the  relation  of  its  depth  to  its  length.  A 
long  wasteway  may  permit  the  loss  of  too  great  a  volume  of 
water  if  exposed  to  the  action  of  the  wind,  whereas  a  short  one 
renders  it  necessary  to  give  the  dam  an  increased  height  in  order 
that  it  may  have  the  required  capacity.  The  depth  of  the  waste- 
way  will  be  largely  regulated  by  the  probable  wave-height,  and 
this  will  depend  on  the  depth  and  fetch  of  the  reservoir  (Art.  305). 
The  difference  in  height  between  the  crest  of  the  dam  and  the 
wasteway  will  generally  vary  between  5  and  20  feet  as  limits. 
Care  should  always  be  taken,  in  designing  a  wasteway,  rapidly  to 
increase  the  slope  of  its  bed  immediately  below  the  crest  of  the 
waste  weir,  so  that  there  shall  be  no  piling  or  banking  up  of 
water  to  retard  the  discharge.  A  quick  drop  beyond  the  crest 
considerably  enhances  the  discharging  capacity. 
.  368.  Discharge  of  Waste  Weirs. — For  the  calculation  of 
discharge  the  wasteway  can  be  considered  as  a  measuring  weir 
subject  to  the  weir  formulas.  If  the  crest  of  the  wasteway  has 
a  sharp  square  edge  or  falls  away  with  considerable  suddenness 


CLASSES    OF    WASTEWAYS  483 

on  the  lower  side,  Francis'  formula  (Art.  90)  may  be  applied 
with  approximate  results,  and  we  have 

<2  =  3-33('-.i^! (i) 

The  mean  velocity  of  flow  over  the  crest  is 

v  =  %V~2gh, 

and  multiplying  the  depth  of  water  on  the  weir  h  into  its  length  / 
we  get  the  volume  of  discharge. 

When  the  overfall  from  the  crest  is  not  sudden 

<2  =  5-35<M (2) 

in  which  c  is  a  coefficient  of  contraction  with  the  value  of  about 
.62.  Where  the  overfall  weir  has  a  wide  crest  the  following 
formula,  suggested  by  Mr.  Francis,  is  the  most  accurate  for 
depths  between  6  and  18  inches,  viz.  (see  also  Art.  330), 

Q-3.0I2/A1-" (3) 

Another  formula,  and  one  commonly  used  in  India  for  deter- 
mining the  discharge  of  wasteways  is, 

Q  =  I  X  \c  X  8.02\Af", 

in  which  c  is  a  coefficient  which  varies  with  the  form  of  the  weir 
and  rarely  exceeds  .65,  though  with  a  majority  of  weirs  it  is 
about  equal  to  .62.  In  which  case 

Q  -  3-33V*", 

where  d  is  the  maximum  depth  in  feet  of  water  to  be  permitted 
to  pass  over  the  weir.  Ordinarily  there  is  no  velocity  of  ap- 
proach to  a  reservoir  wasteway,  though  should  the  water  reach 
the  latter  by  a  cut  it  may  be  necessary  to  take  the  velocity  of 
approach  into  account. 

369.  Classes  of  Wasteways. — Wasteways  may  be  divided 
into  three  general  classes,  depending  upon  the  character  of  the 
dam  and  the  topography  of  the  site.  First,  the  entire  struc- 
ture, if  of  masonry,  may  be  utilized  as  a  wasteway.  This  can 
only  be  done  by  making  the  cross-section  of  the  dam  unusually 
heavy  and  providing  it  against  the  shock  of  falling  water,  as  in 
the  case  of  the  Folsom,  La  Grange,  Betwa,  Colorado  River,  Spier 
Falls,  McCall's  Ferry,  and  Vyrnwy  dams  (Articles  353  to  358). 
Second,  if  the  dam  is  of  masonry  it  may  be  given  the  theoretical 


484  WASTEWAYS    AND    OUTLET    SLUICES 

cross-section  and  the  wasteway  made  in  one  end  of  it,  if  the  dam 
at  this  point  is  sufficiently  low  not  to  subject  it  to  great  shock  from 
the  falling  water.  This  is  the  case  with  the  Bhatgur,  Tansa,  and 
New  Croton  dams  (Articles  345  to  347). 

It  is  never  advisable  to  build  a  wasteway  in  earth  or  loose 
rock  dams,  as  it  is  difficult  to  make  a  safe  bond  between  the 
masonry  wasteway  and  the  earth  dam,  and  unless  extraordi- 
nary circumstances  demand  it  such  an  arrangement  should  be 
avoided.  In  some  cases,  however,  this  has  been  done,  great 
care  being  taken  in  connecting  the  two  classes  of  work,  and  the 
wasteway  being  carefully  lined  with  masonry  and  provided 
with  masonry  wing-walls  for  the  protection  of  the  earth  em- 
bankment, as  in  the  Carmel  reservoir  (Article  297). 

The  third  general  class  of  wasteways  is  where  these  are  built 
in  the  hillsides  at  some  distance  from  the  dam.  If  on  the  slopes 
adjacent  to  one  end  of  the  dam,  the  discharge-water  must  be 
so  directed  by  retaining-walls  that  it  will  flow  back  into  the  stream 
channel  clear  of  the  toe  of  the  dam.  Such  wasteways  may  be 
excavated  in  the  solid  rock,  or  if  in  earth  they  should  be  paved 
or  lined  with  masonry.  The  safest  disposition  for  the  wasteway 
is  at  some  favorable  point  in  the  rim  of  the  reservoir  entirely 
free  and  away  from  the  dam.  This  may  be  through  some  low 
saddle,  which  if  too  low  may  be  filled  in  with  a  waste  weir  of 
masonry,  or  if  too  high  may  be  excavated  to  the  proper  elevation. 
Such  an  isolated  channel  is  frequently  found  beyond  some  spur 
immediately  adjacent  to  one  end  of  the  dam  and  discharging 
back  through  a  separate  channel.  This  is  the  case  in  the  Oak 
Ridge  reservoir  dam  in  New  Jersey,  the  Ashokan  reservoir  in  the 
Catskills,  N.  Y.,  the  Ashti  and  Periar  dams  in  India,  and  the  Pecos 
and  Idaho  dams  in  the  West. 

370.  Shapes  of  Waste  Weirs. — The  forms  of  waste  weirs 
for  dams  vary  considerably  with  the  circumstances  under  which 
they  are  constructed.  Their  general  design  is  very  similar  to 
that  of  weirs  used  for  purposes  of  diversion  (Chapter  X).  They 
may  be  given  the  ogee  shape  (Article  1 76)  in  order  that  the  water 
falling  over  them  shall  produce  the  least  vibration  in  the  structure; 
or  water-cushions  may  be  employed  to  deaden  the  effect  of  the 


486  WASTEWAYS    AND    OUTLET    SLUICES 

falling  water  (Article  177).  Other  of  the  more  usual  and  more 
popular  forms  are  the  wide-crested  overfall  dam  (Articles  329 
and  330),  and  the  stepped  overfall  weir  used  in  the  Croton  reser- 
voirs (Fig.  165). 

371.  Examples  of  Wasteways. — Brief  descriptions  and  illus- 
trations of  wasteways  were  given  in  Articles  346  to  348.  The 
wast ew ay  of  the  Sweetwater  dam  (Art.  352)  is  peculiar.  It  is  built 
as  a  continuation  of  the  main  dam  and,  as  shown  in  Plates  XXVII 
and  XXVIII,  the  water  from  the  reservoir  enters  the  several 
separate  passageways  over  a  waste  weir  and  drops  into  a  shallow 
water-cushion.  Thence  it  flows  through  a  channel  partly  ex- 
cavated in  the  side  of  the  ravine  and  partly  constructed  by  means 
of  an  artificial  wall  which  carries  the  water  clear  of  the  toe  of 
the  dam.  The  wasteways  to  the  Periar  dam  are  two  in  number, 
one  at  either  end  of  the  structure;  both  are  separated  from 
the  main  dam  by  low  saddles  of  rock.  That  on  the  right  bank 
is  cut  down  for  a  length  of  420  feet  till  its  crest  is  1 1  feet  below  that 
of  the  main  dam.  On  the  left  bank  the  solid  rock  is  50  feet  below 
the  crest  of  the  dam,  and  the  saddle  is  closed  with  a  waste  weir 
of  masonry  built  up  to  the  same  level  as  that  of  the  wasteway  on 
the  other  bank.  The  Roosevelt  dam  (PL  XXXII)  is  flanked  at 
either  end  with  ample  wasteways  excavated  in  the  solid  rock 
abutments,  which  discharge  through  deep  hewn  channels  well 
below  the  toe  of  the  dam. 

A  similar  waste  weir  to  that  just  described,  and  one  some- 
what similarly  situated,  is  that  at  the  Idaho  Mining  and  Irriga- 
tion Company's  dam  described  in  Article  308.  The  wasteway 
of  the  Ashti  tank  in  India  consists  of  a  channel  having  a  clear 
width  of  800  feet  excavated  through  a  saddle  in  the  high  ridge 
bounding  the  reservoir  on  its  western  side.  The  bed  of  this 
channel  at  its  entrance  forms  the  weir  crest,  and  is  level  for  a 
length  of  about  600  feet  and  then  falls  away  with  a  slope  of  i 
in  100  to  a  side  drainage  channel.  The  dam  is  12  feet  in  height 
above  the  crest  of  the  wasteway,  and  the  greatest  flood  anticipated 
would  raise  the  w^ater  in  this  wasteway  to  7  feet  above  its  crest, 
or  to  within  5  feet  of  the  top  of  the  dam — just  sufficient  to  prevent 
waves  from  topping  it. 


EXAMPLES    OF   WASTEWAYS 


487 


Interesting  types  of  wasteways  to  earth  dams  are  those  for 
some  of  the  Croton  water-shed  reservoirs,  and  that  for  the  Santa 


Fe  dam.  The  Carmel 
closed  by  an  earth 
dam,  260  feet  in  length 
of  the  center  being 
occupied  by  a  masonry 
overfall  weir  and  gate- 
house. This  masonry 
wasteway  is  bonded 
with  the  earth  dam 
through  the  masonry 
core-walls,  and  by  pro- 
tecting wing-  or  retain- 
ing-walls  of  masonry. 
The  maximum  height 
of  the  waste  weir  is  65 
feet,  and  the  crest  of 
the  earth  dam  is  12 
feet  higher.  The  waste 
weir  has  a  cross-sec- 
tion similar  to  that  of 
the  new  Croton  dam 
(Fig.  165). 

Above  the  Santa 
Fe  earth  dam  is  an  old 
masonry  dam,  the  crest 
of  which  has  been  cut 
down  to  the  level  of 
the  wasteway  of  the 
earth  dam,  which  is 
10  feet  lower  than  its 
crest.  The  old  dam 
serves  to  check  and 


reservoir  of  the  Croton  watershed  is 


SECTION  A 

SHOWING  MOUTH 
OF  TUNNEL. 


SECTION  C-D 


FIG.  182. — Plan  of  Santa  Fe  Reservoir,  showing 
Arrangement  of  Wasteway  and  Cross-section 
of  Waste-weir. 


cause  the  deposit  of  sediment  above  it,  and  this  is  to  be  sluiced 
off  through  an  undersluice  and  tunnel  terminating  in  the  waste- 
way  of  the  dam  (Fig.  182).  When  the  flood  flow  exceeds  the 


488 


WASTEWAYS    AND    OUTLET    SLUICES 


capacity  of  the  tunnel  it  will  pass  over  the  old  dam  and  be  dis- 
charged through  the  main  wasteway.  This  is  at  one  end  of  the 
earth  dam,  is  semicircular,  with  a  radius  of  150  feet,  and  is  471 
feet  long  on  its  crest  so  as  to  give  an  increased  discharge  area  on 
a  minimum  available  length.  Its  summit  is  closed  by  an  earth 
embankment  with  a  masonry  core-wall,  and  heavily  paved  with 
stone,  its  slope  being  very  gentle. 

372.  Automatic  Shutters  and  Gates. — The  use  of  flashboards 
or  any  similar  permanent  obstruction  in  a  wasteway  in  order  to 
increase  the  storage  capacity  of  the  reservoir  is  greatly  to  be  con- 
demned. Such  obstructions  must  be  removed  at  the  time  of 
great  floods  or  else  these  will  top  the  dam.  The  result  of  their 
use  is  that  the  area  of  the  wasteway  is  diminished  below  the  point 
of  safety,  while  the  integrity  of  the  structure  depends  upon  the 
careful  attention  of  the  watchmen,  who  should  remove  the  flash- 


FlG.  183. — Cross-section  of  Shutter  on  Soane  Weir,  India. 

boards.  Automatic  shutters,  however,  have  been  used  with 
considerable  success  in  a  few  instances.  These,  however,  should 
only  be  employed  where  water  is  of  the  greatest  value  and  the 
saving  of  every  drop  is  essential. 

One  of  the  most  desirable  forms  of  these  is  that  shown  in 
Fig.  183.  It  consists  of  a  row  of  upright  iron  shutters,  each 
1 8  feet  long  and  22  inches  high.  These  are  supported  by  struts 
or  tension-rods  hinged  to  the  crest  of  the  weir  on  the  up-stream 
side,  and  to  the  upper  side  of  the  shutter  at  about  two-thirds  of 
the  distance  from  its  crest,  or,  in  other  words,  below  its  center 
of  pressure.  As  soon  as  the  water-level  approaches  the  top  of 
the  shutter  it  causes  its  lower  end  to  slide  inward  and  the  whole 
falls  flat  against  the  top  of  the  weir,  offering  no  obstruction  to 
the  passage  of  the  water. 


AUTOMATIC   DROP-SHUTTERS 


489 


373.  Automatic  Drop-shutters. — These  shutters,  added  in 
1901  to  the  crest  of  the  Betwa  weir  at  Paricha,  India,  to  increase 
the  reservoir  capacity  (Article  355)  may  be  taken  as  illustrative 
of  the  latest  Indian  practice  in  the  design  of  automatic  drop- 


Anchoo 


631.90 


OLD  WEiR  RUB.  MASONRY. 
12'0- 


\     M.S.Plate 

\  / 

\  / 

\         / 

\      / 

— 5e 


/        M.S.  Plato 


Shoe./       ELEVATION. 


'L.I.  Stiffer 


X  Plate 


SECTION 


« 


,L.I. 


/L.I.  Brace 


IB-  J° 


Sfer 


Shoe 


^L.I.  Stiffener  3X  x  2X  x  H 
BOTTOM  PLAN. 

FIG.  184. — Automatic  Drop-shutter,  Betwa  Weir,  India. 

shutters.  Moreover,  these  shutters  were  subjected  to  an  unusual 
test,  immediately  after  completion,  in  the  form  of  an  extraordinary 
flood  which  passed  over  the  weir  crest  to  the  height  of  16.4  feet, 
when  it  had  been  designed  to  withstand  a  previous  known  flood 


49° 


WASTEWAYS    AND   OUTLET   SLUICES 


height  of  only  6.5  feet.  Fortunately  the  shutters  worked  suc- 
cessfully and  neither  weir  nor  shutters  sustained  material  injury. 
The  shutters  are  each  6  feet  high  and  12  feet  long,  and  as 
the  length  of  the  weir  crest  is  3600  feet  there  are  300  such  shutters. 
They  are  made  entirely  of  steel,  consisting  of  \"  plates  joined 
along  their  middle  and  stiffened  both  longitudinally  and  laterally 
by  angle-iron  3iX"X2j"f"  (Fig.  184).  To  the  flanges  of  the 
vertical  stiff eners  are  pivoted  if"  tension-bars.  The  other  end 
is  similarly  attached  to  anchor-bolts  built  2  feet  into  the  masonry 
crest  of  the  weir.  There  are  four  such  tension-bars  to  each  1 2 -foot 


FIG.  185. — Attachment  of  Tension-rod  to  Drop-shutter. 

gate.  The  point  of  attachment  of  the  tension-bar  and  shutter 
is  so  designed  that  the  gates  fall  automatically  with  a  given  depth 
of  water  passing  over  them,  thus  securing  safety  in  case  of  exces- 
sive floods.  The  bottom  of  each  gate  is  supplied  with  four  steel 
shoes,  which  rest  upon  si  id  ing- plates  built  into  the  weir  crest, 
thus  reducing  the  frictional  resistance  when  the  gates  fall. 
Wooden  baulks  4"X4"  are  fixed  to  the  ends  of  the  shutters,  which 
have  a  space  of  i"  separating  them,  which  is  caulked  when  the 
gates  are  raised. 

If  the  300  shutters  were  to  fall  together  the  shock  would 
unduly  strain  the  weir  and  the  flood  volume  submerge  the  river- 


AUTOMATIC    WEIR-GATES 


491 


banks  below.  Hence  the  attachment  of  the  tension-bars  has 
been  so  arranged  that  each  third  gate  falls  under  different  depths 
of  water.  The  first  third  fall  with  a  depth  over  top  of  2  feet, 
the  next  with  3  feet,  and  the  last  with  4  feet.  Thus  after  the 
first  third  fall  the  released  water  reduces  the  flood  depth,  and 
the  latter  must  increase  considerably  to  top  the  second  third, 
and  so  on  for  the  last  third.  It  was  not  anticipated  that  all  the 
shutters  would  ever  fall,  yet  this  occurred  in  the  flood  above 
mentioned. 

As  a  fraction  of  an  inch  would  make  a  great  difference  in 
upsetting  the  gate,  careful  calculations  and  experiments  were 
made  with  a  model  gate  to  determine  the  exact  point  of  attach- 
ment of  the  tension-rods  (Fig.  185).  So  as  to  have  uniformity 
of  length  of  the  latter  the  pivot-holes  in  the  shutters  were  arranged 
in  an  arc  of  circle,  at  the  required  height  from  the  bottom  of  the 
shoe,  in  the  following  manner: 


Hole. 

H. 

Depth  to  Upset. 

I 

2' 

or 

2' 

2 

2' 

if* 

3' 

3 

2' 

af 

4' 

374.  Automatic  Weir-gates. — An  ingenious  automatic  weir- 
gate  (PI.  XXXVI),  devised  by  Mr.  E.  K.  Remold  for  the  Bhatgur 
reservoir,  India,  is  of  value  where  water  is  precious,  and  can  be 
utilized  with  considerable  safety  to  retain  water  to  the  full  storage 
capacity  of  the  reservoir.  The  gate  falls  automatically  as  soon 
as  the  water  reaches  its  crest,  and  continues  to  fall  as  the  flood 
rises  until  the  full  discharge  capacity  of  the  wasteway  is  brought 
into  action.  The  gate  then  closes  as  the  flood  subsides,  enabling 
the  reservoir  to  retain  the  maximum  amount  of  water. 

The  gate  slides  vertically  on  two  contact  surfaces,  one  of 
which  is  the  face  of  the  wasteway  against  which  it  presses  while 
the  other  surface  is  attached  to  the  face  of  the  gate.  These 
surfaces  slide  parallel  to  each  other  and  are  the  surfaces  of  in- 
clined planes.  The  gate  rests  on  wheels  running  on  rails,  and 
the  axes  of  the  wheels  are  parallel  to  the  line  of  the  rails  and  at 


492 


WASTEWAYS    AND    OUTLET    SLUICES 


)nry 


Dam 


PLAN. 


Fixed  Metal  Frame 


Open 
Waste  Way 


.Wheel 


Masonry 


Dam 


CROSS  SECTION, 


PLATE.  XXXVI. — Reinold's  Automatic  Waste  Gate,  India. 


TM; 

UNIVERSITY 

\T   AI  o^     y 

i^^N-glt)NEY'S    BALANCED    SLUICE-GATE  493 

a  slight  angle  to  the  contact  planes  so  that  the  latter  do  not 
touch  until  the  gate  is  fully  raised  or  closed,  thus  permitting  by 
leakage  a  large  amount  of  flood-water  to  run  out  of  them  until 
the  last  moment.  The  gates  are  operated  by  means  of  counter- 
poises balanced  in  water  cisterns,  the  weight  of  these  counter- 
poises exceeding  the  weight  of  the  gate  by  a  little  more  than  the 
amount  of  friction,  and  they  act  by  displacing  their  volume  in  the 
water  cisterns  in  which  they  plunge,  thus  lessening  their  weight 
by  that  volume  of  water.  As  the  water  flows  over  the  top  of 
the  gate  it  simultaneously  enters  the  cast-iron  cisterns  in  which  the 
counterweights  hang.  When  the  water  ceases  to  enter  the  cisterns, 
owing  to  its  level  having  fallen  below  that  of  the  inlets,  it  runs 
out  from  holes  in  the  bottom  and  the  weights  then  become  heavier 
than  the  gate  and  raise  it. 

375.  Stoney's  Balanced  Sluice-gate. — This  shutter  was  de- 
signed and  built  to  close  the  inlet  at  the  head  of  the  tunnel  which 
discharges  the  water  from  Periyar  reservoir  (Article  348)  through 
the  watershed  divide  into  the  drainage  basin  of  the  Madura  valley, 
which  it  irrigates.  The  original  idea  as  to  the  mode  of  operation 
of  this  shutter  was  probably  derived  from  the  Reinold  automatic 
weir  (Article  374),  but  it  has  necessarily  been  modified  therefrom, 
as  it  is  to  sustain  a  considerable  head  of  water  as  compared  with 
the  latter,  which  is  built  in  the  top  of  a  waste  weir. 

The  section  of  the  outlet  tunnel  is  96  square  feet.  The  max- 
imum velocity  of  water  12  feet  per  second.  The  sluiceway 
opening  has  dimensions  of  12  feet  9  inches  high  by  9  feet  6  inches 
wide,  giving  an  increased  area  of  118}  square  feet.  The  maxi- 
mum pressure  on  the  sluice-gate  is  due  to  a  head  of  48.5  feet. 
The  lift  of  the  shutter  is  8J  feet,  and  it  is  protected  from  driftwood 
by  a  grating  12  feet  high. 

The  mechanism  consists  of  a  groove  in  the  masonry,  in  which 
is  a  cast-iron  frame,  bolted  together,  and  with  machine-planed 
faces  to  assure  close  contact  (Fig.  186).  United  to  these  casings 
is  a  roller-path  so  that  the  whole  forms  a  rigid  structure.  The 
width  of  the  roller  face  is  14  inches,  to  enable  it  to  withstand  the 
great  pressure.  The  roller-path  is  free  to  "rock,"  and  it  carries 
a  steel  shield-plate  to  protect  the  rollers  against  the  rush  of  water. 


494 


WASTEWAYS    AND    OUTLET    SLUICES 


VERTICAL  SECTlOfOU 
THROUGH  GATE         h 


Feet 


LONGITUDINAL     SECTION 

SCALP 

I     I     I     I     I     I 


012315 


10  Feet 


FIG.  186. — Stoney's  Balanced  Sluice-gate,  Periyar  Dam,  India. 


UNDERSLUICES  495 

The  gate  is  supported  against  the  water-pressure  by  20  pairs  of 
cast-iron  rollers  and  is  of  exceptional  strength,  being  of  J-inch 
steel  plate.  The  surface  of  the  gate  is  supported  by  14  steel 
beams,  each  14  by  6  inches,  which  transmit  the  load  to  the  roller 
bearings.  It  is  operated  by  a  screw  lifting-gear  and  is  balanced 
to  the  extent  of  two-thirds  its  total  weight.  The  sluice-gate  was 
made  higher  and  narrower  than  the  tunnel  opening,  to  give  it  a 
greater  length  of  roller-path  and  thus  distribute  the  roller-pres- 
sures. 

The  counterweight  moves  in  a  trough  in  the  masonry,  and 
consists  of  a  steel  tank  filled  with  stone  and  carried  by  two  steel 
wire  ropes.  The  lifting-screw  is  a  3j-inch  steel  bar,  double 
threaded,  and  is  operated  by  a  massive  bevelled  wheel  worked 
with  a  winch.  The  nut  is  bolted  to  the  head  of  the  cast-iron  arm, 
which  transmits  the  motion  of  the  gate,  thus  enabling  the  gearing 
to  either  lift  or  push.  A  modification  of  the  Stoney  gate  is  used 
in  the  outlet  tunnel  of  Roosevelt  dam  under  a  head  of  230  feet 
(Art.  381). 

376.  Undersluices. — Undersluices  perform  the  same  func- 
tion for  storage  dams  as  do  scouring  sluices  in  diversion  weirs. 
Their  object  is  to  remove  or  to  prevent  the  deposition  of  sedi- 
ment in  the  reservoir.  Undersluices  have  little  effect  in  pre- 
venting the  deposition  of  silt  unless  the  area  of  their  opening 
is  great  compared  to  the  area  of  the  flood,  while  they  are  use- 
less for  the  removal  of  silt  already  deposited.  This  is  shown 
by  the  manner  in  which  such  reservoirs  as  Lake  Fife  and  the 
Vir  reservoir  in  Bombay,  India,  and  the  Folsom  reservoir  in 
California,  have  silted  up  in  spite  of  them.  If  the  dam  is  high 
and  the  discharge  through  the  Undersluices  will  keep  the  flood- 
level  below  the  full  supply-level,  they  may  be  efficient  in  pre- 
venting the  deposit  of  silt  by  carrying  it  off  in  suspension.  If 
the  dam  is  low  and  the  area  of  the  Undersluices  will  not  enable 
them  to  keep  the  flood-level  below  full  supply-level,  they  will 
have  but  little  effect.  This  has  been  partly  proved  at  the  Betwa 
and  Bhatgur  reservoirs  in  India,  where  experience  shows  that 
their  scouring  or  preventive  effect  is  felt  but  a  few  feet  to  either 
side  of  the  sluice,  and  silt  will  deposit  close  to  the  entrance.  In 


496  WASTEWAYS    AND    OUTLET    SLUICES 

other  words,  undersluices  do  little  more  than  keep  an  open  channel 
above  them. 

377.  Examples   of   Undersluices. — The   most   successful    at- 
tempt to  utilize  undersluices  for  the  clearance  of  silt  is  at  the 
Bhatgur  reservoir  in  India.     There  are  fifteen  undersluices  in 
the  center  of  the  dam  near  its  bottom,  their  sills  being  60  feet 
below  high- water  mark  (PL  XXV).     Each  of  these  undersluices 
is  4  by  8  feet  in  interior  dimensions,  and  they  are  lined  throughout 
with  the  best  ashlar  masonry.     Under  a  full  head  they  will  dis- 
charge 20,000  second-feet,  and  the  velocity  through  them  is  36 
feet  per  second.     Each  undersluice  is  closed  by  a  heavy  iron  gate, 
which   slides   vertically   and   weighs   about   2   tons.     They   are 
operated  by  steel  screws  worked  from  above  by  a  female  capstan 
screw  turned  by  hand-levers.     Stout  wooden  gratings  protect 
the  gates  from  injury  by  floating  objects.     The  undersluices  are 
placed  about  30  feet  apart,  and  the  space  between  filled  with 
sediment  shortly  after  the  completion  of  the  dam. 

In  the  bottom  of  the  Folsom  dam  in  California  there  is  a  set 
of  three  undersiuices,  the  object  of  which  is  to  remove  silt  depos- 
ited in  the  reservoir  (PL  XXXI).  These  undersluices  are  built 
in  the  center  of  the  weir  near  its  bottom,  and  are  under  a  head 
of  60  feet,  the  area  of  each  one  being  4  by  4  feet.  While  these 
undersluices  have  not  impaired  the  integrity  of  the  structure 
they  have  been  of  little  service  in  preventing  the  deposit  of  silt, 
as  their  area  compared  with  that  of  the  floods  is  small. 

378.  Outlet  Sluices. — As  the  object  of  a  storage  dam  is  to 
impound  water  that  may  be  drawn  off  when  wanted,  one  or 
more  outlet  sluices  must  be  constructed  at  the  level  at  which  water 
is  to  be  drawn  off.     These  outlet  sluices  either  terminate  in  pipe 
lines  which  carry  the  water  to  the  point  of  distribution  or  dis- 
charge directly  into  the  canal  head  or  back  into  the  stream  channel 
to  be  again  diverted  lower  down.     The  greater  the  depth  at 
which  these  sluices  are  placed  the  greater  the  available  capacity 
of  the  reservoir.     They  may  either  be  built  in  the  body  of  the 
dam  or  through  the  confining  hillsides  independently  of  the  dam. 
The  latter  is  by  far  the  better  and  safer  method,  and,  wherever 
practicable,  should  be  employed,  as  anything  which  breaks  the 


OUTLET    SLUICES  497 

homogeneity  of  the  dam  is  a  menace  to  its  integrity.  With  an 
earth  dam  this  is  especially  true,  and  its  greatest  source  of  weak- 
ness is  the  discharge  conduit  passing  through  it. 

Simple  pipes  should  never  be  laid  through  an  earth  embank- 
ment, as  under  the  pressure  of  the  water  in  the  reservoir  this  is 
certain  ultimately  to  find  its  way  along  the  line  between  the  pipe 
and  the  earth  embankment  or  through  a  loose  joint  in  the  pipe, 
and  the  water  which  enters  the  embankment  in  this  manner  will 
rapidly  increase  in  quantity  until  the  structure  is  destroyed. 

It  is  essential  that  the  outlet  sluices,  valves,  pipes,  etc.,  should 
always  be  accessible  for  inspection  and  repair  in  order  that  the 
constant  use  of  the  reservoir  may  not  be  interrupted.  When 
they  must  be  placed  in  the  embankment  a  masonry  conduit 
should  be  built  through  it,  and  for  convenience  of  inspection 
an  iron  pipe  should  be  placed  in  this.  The  conduit  should 
be  of  such  dimensions  that  a  man  can  pass  through  it,  and  the 
pipe  should  be  so  placed  within  it  as  to  be  easily  seen  and  re- 
paired. In  order  to  prevent  the  travel  of  seepage  water  along 
the  outside  of  the  conduit,  rings  of  masonry  should  be  placed 
at  short  intervals  along  its  length,  and  these  should  project  not 
less  than  from  i  to  2  feet  from  its  surface.  The  chief  objec- 
tion to  laying  a  conduit  through  a  dam  is  its  liability  to  fracture 
through  settlement. 

Better  and  safer  than  this  is  to  lay  the  discharge  pipes  in  a 
trench  dug  under  the  foundation  of  the  dam  in  the  surface  rock 
or  soil.  Such  a  trench  should  be  substantially  lined  and  roofed 
with  concrete,  and  will  offer  little  inducement  for  travel  of  seepage 
water.  The  best  method  of  all,  however,  for  the  placing  of  out- 
let pipes  is  to  build  them  through  the  surface  rock  or  soil  of  the 
country,  excavating  a  tunnel  for  this  purpose  and  laying  the 
pipes  in  it,  the  whole  being  away  from  and  independent  of  the 
dam.  This  insures  them  against  any  damage  from  settlement 
in  the  structure. 

Sometimes  the  entrance  to  the  outlet  culvert  is  not  placed 

at  the  lowest  level  of  the  reservoir,  but  at  about  two-thirds  the 

way  up  the  embankment  from  the  bottom,  or  at  such  height 

that  the  pressure  will  enable  a  siphon  to  draw  water  off  from 

32 


498  WASTEWAYS   AND  OUTLET   SLUICES 

the  lowest  depths  of  the  reservoir.  This  siphon  pipe  is  carried 
down  to  the  bottom  of  the  reservoir,  and  passes  up  through  the 
culvert,  in  which  is  placed  the  main  pipe  connected  with  the 
valve-chamber  and  supplied  directly  from  orifices  above  the 
level  of  the  conduit  (Fig.  187).  Where  a  reservoir  embankment 


FIG.  187. — Outlet  Pipes  and  Siphon  in  Earth  Dam. 

is  very  low — say  25  feet  or  under — it  may  be  discharged  by  simply 
carrying  a  siphon  pipe  over  the  top  of  the  embankment  with  no 
outlet  pipe  or  conduit  through  the  embankment. 

379.  Gate-towers  and  Valve-chambers. — The  valves  for  con- 
trolling the  admission  of  water  to  the  outlet  sluice  are  either 
operated  from  a  valve-chamber  let  into  the  body  of  the  dam  or 
from  a  gate-tower  situated  in  the  reservoir  at  a  point  over  the 
inlet  to  the  discharge  conduit.  In  order  that  these  valves  shall 
not  be  worked  under  too  great  pressure  water  is  usually  admitted 
to  the  tower  or  well  from  orifices  placed  at  several  depths,  and  in 
this  well  the  conduit  heads.  At  its  exit  at  the  lower  side  of  the 
dam  is  generally  placed  a  second  valve-chamber  or  gate-house 
for  the  control  of  water  which  is  admitted  to  the  distributing  pipes 
or  canal.  The  orifices  admitting  water  to  the  well-tower  are 
closed  on  the  outside  by  plugs  or  close-fitting  valves,  which  can 
be  operated  from  the  top  of  the  tower  or  valve-chamber;  while 
the  valve  admitting  the  water  from  the  bottom  of  the  well  to  the 
outlet  sluices  is  operated  either  from  the  tower  or  from  the  bottom 
of  the  well-pit  by  screws  and  hand-gearing.  In  this  manner  the 
attendant  in  charge  has  full  control  of  the  whole  outlet  works, 
and  all  pipes  and  valves  are  under  perfect  control  so  that  the 
supply  can  at  any  time  be  arrested  for  the  repair  of  pipes.  In  case 
a  gate-tower  is  constructed  independently  of  and  away  from  the 
body  of  the  dam,  great  care  must  be  taken  to  make  it  sufficiently 


GATE-TOWERS    AND    VALVE-CHAMBERS 


499 


substantial  to  withstand  the  thrust  of  ice,  or  it  should  be  buttressed 
against  the  side  of  the  dam. 

The  outlet  sluice-pipe  which  passes  through  the  embank- 
ment may  be  connected  on  the  inside  of  the  reservoir  by  a  flexible 
joint  with  another  pipe  of  the  same  diameter,  to  the  end  of  which 
is  attached  a  float.  This  pipe  can  thus  be  moved  vertically, 
and  admits  of  the  water  being  drawn  off  from  the  surface  where 
the  pressure  on  the  valve  is  the  least.  Where  the  expense  will 
peimit,  the  better  method  is  that  of  admitting  the  water  to  a 
valve-well  through  orifices  situated  at  varying  heights.  One 
of  the  great  difficulties  encountered  is  to  insure  a  constant  dis- 
charge from  the  reservoir  with  a  constantly  varying  head  in  it 
or  in  the  gate-well.  The  usual  method  of  insuring  a  constant 


A.  B. 

FIG.  188. — Valve-plugs;  A,  Sweetwater,  and  B,  Hemet  Dams. 

discharge  is  by  opening  the  valve-gates  controlling  the  admission 
of  water  to  the  outlet  sluice  to  a  greater  or  less  extent,  according 
to  the  amount  of  water  required,  though  automatic  systems  of 
maintaining  a  constant  discharge  irrespective  of  the  head  have 
been  used  with  more  or  less  success  in  a  few  cases. 

The  inlets  to  the  valve-chamber  are  of  two  general  classes. 
Those  illustrated  in  Figure  188  consist  of  a  simple  cast-iron  plug 
let  into  the  top  of  the  pipe,  the  end  of  which  is  bent  upward. 
This  plug  is  held  in  position  by  the  pressure  of  the  water  and  is 
removed  by  a  chain  operated  from  above  by  a  windlass.  In 
Plates  XXVI  and  XXVIII  are  shown  the  method  of  placing  the 


500  WASTEWAYS    AND   OUTLET    SLUICES 

valves  at  varying  heights  and  the  arrangement  of  air-valve  and 
gate-house  at  the  lower  end  of  the  dam. 

Another  method  of  admitting  water  to  the  valve-chamber 
is  by  means  of  rectangular  openings  in  the  side  of  the  chamber, 
on  the  inner  surface  of  which  stop-valves  are  bolted.  These 
are  usually  of  cast  iron,  the  seat  and  bearing  of  t^he  valve  being 
faced  with  bronze  composition.  Above  this  projects  a  screw 
stem  which  is  operated  from  above  by  means  of  a  female  cap- 
stan screw.  Where  the  area  of  such  valves  exceeds  4  or  5  square 
feet,  or  the  pressure  is  more  than  20  to  25  pounds,  some  geared 
motion  is  usually  necessary  to  enable  a  single  man  to  operate 
it.  The  in  Lake  valve  permitting  the  water  to  pass  from  the 
valve-chamber  to  the  outlet  sluice  is  usually  a  sliding-valve, 
working  on  oronze  bearings  and  operated  from  above  by  a  screw 
and  hand  gearing.  It  is  not  unusual  to  employ  more  than  one 
such  valve,  according  to  the  amount  of  water  to  be  admitted 
and  the  consequent  number  of  outlet  pipes  required. 

The  foundations  for  gate-towers  must  be  of  the  most  sub- 
stantial character,  especially  where  they  are  attached  to  loose- 
rock  or  earth  dams,  in  which  case  the  foundation  must  be  carried 
down  to  a  sufficient  depth  to  insure  stability. 

380.  Examples  of  Gate-towers  and  Outlet  Sluices. — Owing 
to  the  low  inclination  of  the  inner  surface  of  earth  embank- 
ments or  loose-rock  dams,  it  is  necessary  to  construct  the  gate- 
tower  controlling  the  outlet  sluice  at  some  little  distance  in  the 
reservoir  so  that  it  shall  come  above  the  entrance  to  the  sluice. 
This  method  of  construction  is  occasionally  employed  on  masonry 
dams,  and  an  excellent  example  of  such  a  work  is  that  illustrated 
in  Plates  XXVII  and  XXVIII,  showing  the  gate-tower  to  the 
Sweetwater  reservoir. 

The  upper  and  lower  valve-chambers  of  the  Wachusett  dam 
of  the  Metropolitan  Water-works  oi  Boston  are  illustrated  in 
section  in  Figure  189.  This  dam  is  of  masonry  and  is  135  feet 
in  maximum  height  above  foundations.  It  is  not  contemplated 
to  draw  off  water  from  this  reservoir  to  a  depth  of  less  than  50 
feet.  To  inspect  and  make  repairs  it  is  necessary  only  to  put 
in  stop-planks  to  a  depth  of  65  feet.  The  entrance  to  the  upper 


501 


c  W^W  r aiir I'-'ir^  f 

t£j5 

SECTIONAL  PLAN  A-A 


SECTIONAL  BOTTOM  PLAN. 


ENLARGED  SECTION  OF  FRAME 

AND  BOLTING  EAR. 


PLATE  XXXVII.— Vertical  Lift  Outlet  Gate,  Fay  Lake  Reservoir,  Arizona. 


502 


WASTEWAYS    AND   OUTLET    SLUICES 


well  has  been  contracted  so  that  the  stop-planks  have  a  span  of 
only  2\  feet,  which  can  be  put  together  in  sections  10  feet  high 
with  a  simple  lifting  apparatus.  The  upper  valve-chamber  is 
built  as  a  well  into  the  up-stream  face  of  the  dam,  near  its  center, 
and  from  which  it  projects  only  about  15  feet. 

A  much  better  practice,  however,  is  that  followed  on  the 
Vyrnwy  dam  in  Wales  and  the  San  Mateo  dam  in  California. 
In  the  case  of  the  former  there  are  two  discharge  sluices  operated 


FIG.  189. — Valve-chambers,  Wachusett  Dam,  Boston. 

from  valve-houses  built  in  the  body  of  the  dam  for  discharging 
compensation-water  back  into  the  stream.  The  main  valve- 
chamber,  however,  for  the  supply  of  water  to  the  aqueduct,  is 
situated  at  a  point  on  the  shore  of  the  reservoir  about  three-fourths 
of  a  mile  distant  from  the  dam,  entirely  independent  of  it,  and 
out  in  the  lake  at  such  a  distance  as  to  control  water  at  nearly 
the  maximum  depth.  The  valves  and  other  mechanisms  em- 
ployed in  this  tower  are  all  operated  by  hydraulic  power  furnished 


EXAMPLES    OF   GATE-TOWERS   AND   OUTLET   SLUICES       503 

from  a  water-wheel  supplied  by  a  small  mountain  reservoir.  In 
the  case  of  the  San  Mateo  dam  (PL  XXVI),  the  valve  tower 
is  situated  at  a  point  quite  independent  of  the  dam,  and  the 
outlet  conduit  passes  through  the  country  rock  at  a  sufficient 
distance  from  the  abutments  of  the  structure  to  be  entirely  free 


X  Steel'  Ro3» 
2'c.to  c. 


SECTION   E-£ 


FIG.  190. — Gate  House,  Conconully  Dam,  Wash. 

from  the  pressure  of  its  possible  subsidence.  As  shown  in  the 
illustration,  water  is  admitted  at  three  different  elevations  through 
inlet  pipes  which  discharge  directly  into  a  main  iron  standpipe 
passing  vertically  through  a  shaft  which  is  the  entire  height  of 
the  dam.  The  entrance  of  this  water  to  the  standpipe  is  con- 


504  WASTE  WAYS   AND   OUTLET   SLUICES 

trolled  by  plunger  valves  operated  by  hand-wheels  and  approached 
by  a  stairway  passing  through  the  tower.  At  the  outer  end  of 
the  discharge  pipe  is  another  gate-well  where  the  main  supply 
is  regulated. 

Conconully  reservoir  of  the  Okanogan  project  in  Washington 
is  closed  by  an  earth  dam  83  feet  high.  The  outlet  is  a  circular 
conduit  of  reinforced  concrete  4'  6"  inside  diameter.  This  is 
controlled  by  a  cast-iron  valve  gate  3'  6"  in  diameter,  placed  in  a 
gate-well  f  square  for  access,  and  operated  from  a  gate  house 
62  feet  above  by  a  steel  shaft  and  geared  wheel.  This  shaft  is 
supported  in  an  inclined  tunnel  5'  10"  in  section  and  103  feet  in 
length,  the  reinforced  concrete  walls  of  which  are  from  15  to  24 
inches  in  thickness  (Fig.  190). 

The  mode  of  drawing  water  from  the  Beetaloo  reservoir, 
Australia,  is  interesting  in  that  no  outlet-valve  tower  is  used. 
The  outlet  pipe  is  carried  through  a  tunnel  in  the  hillside,  and 
on  the  inner  or  reservoir  surface  this  pipe  curves  up  the  slope 
of  the  hill.  Its  entrance  or  extremity  is  63  feet  above  the  out- 
let tunnel.  Twenty-six  feet  lower  down  is  a  second  inlet 
valve,  and  a  third  is  placed  opposite  to  and  level  with  the 
tunnel  entrance.  These  inlet  valves  are  of  common  flap 
pattern,  covered  with  wire  strainers,  and  are  operated  from 
the  crest  of  the  dam  by  shafts  or  rods  ij  inches  in  diameter, 
which  rest  on  pulleys.  These  rods  are  pulled  up  or  pushed 
down  to  open  or  close  the  valves  by  having  a  long  screw  at 
their  upper  ends,  working  in  a  female  screw  turned  by  a  2\- 
foot  hand-wheel. 

A  simple  outlet  gate  (PL  XXXVII),  designed  by  Mr.  J.  D. 
Schuyler  to  be  built  on  the  face  of  Fay  reservoir  dam,  is  adapted 
to  closing  an  outlet  of  either  circular  or  rectangular  form.  The 
gate  is  hung  on  its  center  by  one  heavy  lug,  over  which  the  stem  is 
placed,  expanded  to  the  form  of  a  flat  eye-bolt,  having  sufficient 
play  to  enable  the  gate  to  accommodate  itself  to  its  seat  freely,  to 
which  it  is  forced  by  inclined  planes  on  six  lugs  and  guides.  The 
frame  cf  the  hoisting  apparatus  rests  on  top  of  the  masonry,  to 
which  it  is  anchored,  and  the  nut  and  bevelled  gear  are  of  hard 
brass.  Ball  bearings  are  fitted  under  the  nut,  and  a  light  capstan 


EXAMPLES    OF   GATE-TOWERS   AND   OUTLET   SLUICES       505 


3- — •^y~tM . 'KO/CT  /f/*ss...Y*°'CT  °F^  * 
S4>.-i;r  P^N.     3N 


PLATE  XXXVIII.— Outlet  Gates,  Roosevelt  Dam,  Arizona. 


506  WASTEWAYS   AND   OUTLET   SLUICES 

wheel  takes  the  place  of  the  ordinary  crank,  rendering  the  gate 
easily  handled  under  the  maximum  head  of  25  feet. 

381.  Electrically  Operated   Outlet  Gates,  Roosevelt  Dam.— 
The  outlet  tunnel  passes  around  the  left  end  of  the  dam  through 
the  solid  quartzite  cliff.     It  is  490  feet  long,  12  ft.  wide,  and  10  ft. 
high,  its  bottom  being  240  feet  below  the  dam  crest.     Above  the 
gates  the  tunnel  widens  to  a  gate  chamber  19 J  ft.  wide,  which  is 
divided  into  three  channels  by  two  piers  made  of  hollow  cast- 
steel  columns,   filled  with  concrete,   in  which  the  service  and 
emergency   gates    are    supported     (PL    XXXVIII).     Over   the 
gate  chamber  is  a  gallery  of  about  the  same  dimensions,  divided 
into  rooms  by  partitions,  and  containing  recesses  into  which  the 
gates  are  raised. 

The  service  gates  for  regulating  outflow  are  near  the  down- 
stream end  of  the  chamber,  and  the  emergency  gates  for  use  in 
repairs  are  10  feet  further  up-stream.  The  gates  are  each  n  ft. 
6  in.  high  by  6  ft.  4  in.wide,  of  cast  iron  sHding  in  cast-steel  guides. 
The  shell  of  each  is  2\  inches  thick  and  is  strengthened  with  ribs 
of  equal  thickness  spaced  12  inches  centers  and  of  13  in.  depth. 
Each  gate  weighs  10  tons  complete  and  is  surrounded  by  a  bronze 
facing  on  all  edges,  as  is  also  the  gate  frame.  The  gate  and  frame 
each  have  roller  tracks  parallel  to  the  gate  body  but  sloping  away 
from  the  gate  seats  in  opposite  directions  with  a  batter  of  i  in  30. 
When  the  gate  is  closed  the  battered  faces  are  in  contact  and  the 
gate  seats  bear  the  pressure.  The  rollers  are  of  Tobin  bronze, 
each  4  in.  diameter  and  5T9^-  in.  long,  and  in  each  train  are  31 
such  rollers  spaced  3T3g-  inches  apart. 

Each  gate  is  under  800,000  Ibs.  pressure,  and  is  raised  and 
lowered  from  a  hydraulic  cylinder,  in  an  overhead  chamber, 
operating  under  a  maximum  pressure  of  700  Ibs.  per  sq.  in.,  by 
a  bronze  lifting  rod  6  in.  diameter  and  32  ft.  long.  Each  cylinder 
is  operated  by  an  electrically  actuated  pump  outside  the  dam, 
serving  through  two  pipes. 

382.  Unit  Cost  of  Construction. — The  cost   of  construction 
on  contracts  for  the   Reclamation   Service  is  set  forth  in  Art. 
422. 


WORKS   OF   REFERENCE  507 

Earth  Embankments: 

Excavation 25  to  60  cts.  cu.  yd. 

Embankment 20  to  50    "      " 

Riprap $1.50  to  $2.00  sq.  yd. 

Puddle $0.50  to  $i  .25  cu.  yd. 

Dry  paving $2.00  to  $3.50  sq.  yd. 

Sodding 20  to  50  cts.  sq.  yd. 

Masonry  Dams: 

Earth  excavation $  0.25  to  $  0.60  cu.  yd. 

Rubble  masonry  (nat.  cem.) $3.501085.00     "     " 

"       (Port,  cem.) S  4.00  to  $  6.50     ' 

Brick  masonry  (nat.  cem.) Sio.oo  to  S  15.00  "     " 

Dimension  stone  for  works $15 .00  to  S  20.00  "     " 

Rock  excavations $  i.oo  to  S  2.50     " 

Concrete  masonry  (nat.  cem.) $  4.00  to  $  5.50     " 

"        (Port,  cem.) $4.501087.00     "     " 

Rockfaced  ashlar $10.00  to  $30.00     "     " 

Pipes,  Cost  per  Foot  (including  fitting  and  laying): 

12"          1 8"          24"          36"          48"  60"  72" 

Cast-iron $1.60     $2.75     $4.00     $7.00     $12.00     $16.00     $22.00 

Steel-riveted 0.60       1.50       3.00       5.00         6.75         8.50       10.00 

Wooden  stave 1.20       2.00       3.25       5.00         5-25         9-5°       I2-25 

Artesian  Wells  per  Foot: 

2  in.  wells,  $0.50  to  $1.00,  for  300  ft.  to  1000  ft. 
6  to  8  in.  wells,  below  500  ft.,  $2.00  to  $3.00. 
6  to  8  in.  wells,  up  to  1500  ft.,  $3.00  to  $6.00. 
Loose  material  less  than  rock  for  shallow  and  more  than  rock  for  deep  wells. 

383.  Works   of   Reference.     Storage    Works. 

BAKER,  IRA  O.  A  Treatise  on  Masonry  Construction.  John  Wiley  &  Sons, 
New  York,  1890. 

BOVEY,  H.  T.     A  Treatise  on  Hydraulics.     John  Wiley  &  Sons,  New  York,  1895. 

BUCKLEY,  R.  B.  Irrigation  Works  in  India  and  Egypt.  E.  &  F.  N.  Spon,  Lon- 
don, 1893. 

CHURCH,  IRVING  P.  Mechanics  of  Engineering.  Fluids.  John  Wiley  &  Sons, 
New  York,  1889. 

CLERKE,  SADASEWJEE  and  JACOB.  Impounding  Reservoirs  in  India.  Trans. 
Inst.  C.  E.,  No.  2730,  London,  1894. 

FANNING,  J.  T.  Hydraulic  and  Water-supply  Engineering.  D.  Van  Nostrand 
&  Co.,  New  York,  1896. 

FRANCIS,  J.  B.  High  Walls  or  Dams  to  Resist  the  Pressure  of  Water.  Trans. 
Am.  Soc.  C.  E.,  New  York,  vol.  xix,  1888. 

FTELEY,  A.  Report  of  Chief  Engineer  of  Croton  Aqueduct  Commission,  New 
York,  1895. 

GOULD,  B.  SHERMAN.  Contract  and  Specifications  for  Building  a  Masonry  and 
Earthen  Dam.  Engineering  News  Pub.  Co.,  New  York. 

HALL,  WM.  HAM.  Irrigation  in  Southern  California.  Report  as  State  Engineer 
of  Cal.  Sacramento,  1888. 

HOBART,  E.  F.  Reservoir  at  Santa  Fe\  N.  M.  Trans.  Am.  Soc.  Irrigation  En- 
gineers, Denver,  Col.,  1893. 


508  WASTEWAYS    AND    OUTLET    SLUICES 

JACOBS,  ARTHUR,  and  GOULD,  B.  SHERMAN.  The  Designing  and  Construction  of 
Storage  Reservoirs.  D.  Van  Nostrand  &  Co.,  New  York,  1888. 

KRANTZ,  J.  B.  A  Study  on  Reservoir  Walls.  Translated  by  F.  Mahan.  John 
Wiley  &  Sons,  New  York,  1883. 

MACKENZIE,  A.  T.  History  of  the  Periyar  Project.  Superintendent  of  Govern- 
ment Press,  Madras,  India,  1899. 

McCuLLOH,  W.  The  Construction  of  a  Water-tight  Masonry  Dam.  Trans.  Am. 
Soc.  C.  E.,  vol.  xxviii,  New  York,  1893. 

MCMASTERS,  JOHN  B.  High  Masonry  Dams.  D.  Van  Nostrand  &  Co.,  New 
York,  1876. 

MERRIMAN,  MANSFIELD.  Text-book  on  Retaining  Walls  and  Masonry  Dams. 
John  Wiley  &  Sons,  New  York,  1892. 

Reclamation  Service,  U.  S.     Annual  Reports.     Washington,  D.  C. 

RONNA,  A.     Les  Irrigations.     2  vols.     Firmih-Didot  et  Cie,  Paris,  1889. 

SCHUYLER,  JAMES  D.  The  Use  of  Asphaltum  for  Reservoir  Linings.  Trans.  Am. 
Soc.  C.  E.,  vol.  xxvii,  New  York,  1892. 

SCHUYLER,  JAMES  D.  Reservoirs  for  Irrigation,  Water  Power,  etc.  John  Wiley 
&  Sons,  New  York  and  London,  1901. 

STANTON,  ROBERT  B.  Notes  on  the  Construction  of  a  Water-tight  Masonry  Dam. 
Proc.  Am.  Soc.  C.  E.,  vol.  xxii,  New  York,  1896. 

TURNEAURE,  F.  E.,  and  RUSSELL,  H.  L.  Public  Water  Supplies.  John  Wiley  & 
Sons,  New  York,  1901. 

UNITED  STATES  GEOLOGICAL  SURVEY,  i2th,  i3th,  and  i8th  Annual  Reports.  Gov- 
ernment Printing  Office,  Washington,  D.  C.,  1891,  1892,  and  1897. 

VISCHER,  HUBERT,  and  WAGONER,  LUTHER.  On  Strains  in  Curved  Masonry 
Dams.  Trans.  Tech.  Soc.  Pacific  Coast,  vol.  xi,  1890. 

WEGMANN,  EDWARD,  JR.  Design  and  Construction  of  Dams.  John  Wiley  & 
Sons,  New  York,  1*907. 

WEISBACH,  P.  J.,  and  Du  Bois,  A.  JAY.  Hydraulics  and  Hydraulic  Motors. 
John  Wiley  &  Sons,  New  York,  1889. 


CHAPTER  XIX 

PUMPING,    TOOLS,    AND    MAINTENANCE 

384.  Pumping  or  Lift  Irrigation. — The  methods  of  irri- 
gating so  far  considered  are  those  in  which  the  water  is  brought 
to  the  irrigable  land  by  gravity  or  natural  flow.  There  are 
large  volumes  of  water  situated  at  such  a  low  level  that  gravity 
will  not  carry  it  to  the  fields,  and  this  water  must  be  raised  by 
means  of  pumps  or  other  lifting  devices.  Pumping  may  be 
employed  to  utilize  the  water  from  wells  or  from  natural  streams 
flowing  at  a  lower  level  than  the  land  irrigated,  or  may  be  em- 
ployed to  raise  water  from  low-service  canals  to  others  at  higher 
levels. 

When  the  gravity  sources  of  supply  have  been  entirely  util- 
ized large  areas  of  land  may  still  be  brought  under  cultivation 
by  the  employment  of  pumps.  As  irrigation  is  practised,  the 
subsoil  becomes  saturated,  the  ground- water  level  is  raised,  and 
much  of  the  water  delivered  by  gravity  systems  thus  finds  its 
way  by  seepage  from  the  fields  into  the  soil  and  may  be  pumped 
up  and  re-employed  in  irrigation,  thus  greatly  adding  to  the  duty 
of  the  ultimate  sources  of  water-supply.  The  value  of  pumping 
for  this  purpose  has  been  recognized  in  the  older  European  and 
Asiatic  countries  for  ages,  and  a  large  proportion  of  the  irriga- 
tion in  Europe,  China,  Japan,  India,  and  Egypt  is  by  means 
of  lifting  (Article  116).  In  Oriental  lands  lifting  is  performed 
almost  wholly  by  animal  or  man  power,  through  various  ancient 
devices  operated  chiefly  by  bullocks  or  men.  In  Italy  quite  a 
deal  of  pumping  is  done  by  machinery,  chiefly  to  raise  water 
from  existing  low-level  canals  to  high-service  canals. 

In  our  country  the  value  of  pumping  as  a  means  of  irriga- 
tion is  scarcely  yet  appreciated.  A  few  windmills  and  water- 

509 


510  PUMPING,    TOOLS,    AND    MAINTENANCE 

wheels  are  utilized  for  this  purpose,  and  a  small  amount  of  pump- 
ing is  done  by  steam-power,  though  the  value  of  the  water-supply 
to  be  derived  from  these  modes  of  lifting  is  sure  to  increase  greatly 
in  the  near  future,  when  its  cheapness  and  adaptability  come 
to  be  fully  recognized.  The  Reclamation  Service  is  providing 
for  the  utilization  of  water  power,  electric-ally  transmitted,  for 
pumping  water  from  wells  in  the  irrigable  lands  of  the  Salt  River 
and  other  projects  (Art.  117). 

A  perusal  of  this  chapter  will  show  that  pumping  as  a  mode  of 
supplying  irrigation  waters,  far  from  being  more  expensive  than 
water  derived  from  gravity  supplies,  generally  furnishes  water 
more  cheaply  than  do  gravity  supplies,  both  in  the  matter  of  first 
cost  of  the  pumping  or  gravity  plant  or  the  equivalent  cost  of 
water  right  (Tables  I,  XVII,  and  XXIII),  and  in  the  matter  of 
the  cost  of  maintenance  and  operation,  equivalent  in  the  gravity 
supply  to  the  annual  water  rental  or  rate  paid.  Moreover,  the 
source  of  water-supply  is  more  directly  under  control  of  the 
irrigator,  and  he  is  troubled  by  none  of  the  vexatious  questions  of 
priority  of  right,  tatils,  etc. 

385.  Motive  Power  and  Pumps. — Pumps  are  machines  for 
elevating  water,  and  consist  of  two  principal  parts:  (i)  the 
pumping  or  water-elevating  mechanism,  and  (2)  the  motive 
power  by  which  this  is  operated. 

Pumps  may  be  divided  into  four  general  classes,  according 
to  the  principle  on  which  they  raise  the  water.  These  are : 

1.  Lift-pumps. 

2.  Force-  or  plunger-pumps. 

3.  Rotary  and  centrifugal  pumps. 

4.  Mechanical  water-elevators. 

Lift-  and  force-pumps  may  be  combined,  and  may  be  either 
reciprocating  or  rotary,  in  which  latter  case  they  come  under 
class  three.  All  may  be  single-  or  double-acting. 

The  motive  power  may  be : 

1.  Animal-power. 

2.  Wind-power. 

3.  Water-power. 

4.  Hot-air  or  gas  engines. 


MOTIVE   POWER   AND    PUMPS  511 

5.  Steam-engines. 

6.  Hydro-electric. 

The  above  classes  of  pumping  machinery  are  nearly  all  in- 
terchangeable. Thus  lift,  force,  and  centrifugal  pumps  and 
mechanical  elevators  may  nearly  all  be  operated  by  any  of  the 
various  motive  powers,  though  not  by  all  of  them. 

Distinguished  from  these  there  are  three  additional  classes 
of  pumping  mechanisms  in  which  the  motive  power  and  pump 
are  inseparable.  These  are: 

1.  Injectors,    vacuum-pumps,    and    pulsometers,    in    which 
steam  is  the  motive  power. 

2.  Hydraulic  rams  and  hydraulic  pumping-engines,  in  which 
water  is  the  motive  power. 

3.  Siphons  and  siphon  elevators,  in  which  atmospheric  pres- 
sure is  the  motive  power. 

Lifting-pumps  operate  by  drawing  water  through  a  suction- 
pipe  as  the  pump  bucket  ascends;  the  water  is  forced  through 
a  valve  in  the  bucket  as  the  plunger  descends,  and  is  then  again 
lifted  as  the  bucket  reascends.  This  variety  of  pump  is  de- 
pendent for  its  operation  on  the  creating  of  a  partial  vacuum 
below  the  pump  bucket  by  atmospheric  pressure. 

Force-pumps  draw  water  through  a  suction-pipe  as  do  lift- 
pumps,  but  the  water  is  raised  above  the  bucket  by  the  action 
of  a  piston  or  plunger  which  forces  it  through  a  delivery  valve. 
Force-pumps  may  be  single-  or  double-acting,  and  nearly  all 
steam-pumps  -are  of  the  latter  variety,  the  discharge  of  these 
being  practically  continuous,  for  as  the  water  is  drawn  in  at 
one  end  it  is  forced  out  at  the  other. 

Centrifugal  pumps  depend  for  their  action  on  a  disk  to  which 
are  attached  propeller-blades  revolving  inside  a  chamber.  These 
propeller-blades  create  a  partial  vacuum  which  lifts  water  into 
the  chamber  by  suction,  whence  it  is  forced  by  the  following 
propeller-blade.  Rotary  pumps  are  practically  revolving  piston- 
pumps,  differing  from  the  latter  chiefly  in  that  they  are  not  direct- 
acting. 

Mechanical  water-elevators  include  the  various  patented  de- 
vices in  which  water  is  raised  by  means  of  disks  or  buckets  ar- 


512  PUMPING,    TOOLS,    AND   MAINTENANCE  . 

ranged  on  a  revolving  chain;  also  chain-pumps,  Archimedean 
screws,  Persian  wheels,  norias,  the  common  well-sweep,  which 
is  the  paecottah  of  India  and  the  sakia  of  Egypt;  and  many 
other  curious  devices. 

All  the  motive  powers  except  wind  may  be  used  to  operate 
any  of  the  various  classes  of  pumps.  Ordinarily,  however, 
animal  power  is  used  to  operate  the  lighter  forms  of  pumping 
machinery  which  are  intended  to  elevate  small  quantities  of  water 
and  the  common  lift-  and  force-pumps  and  mechanical  elevators 
of  various  kinds.  Wind  is  employed  almost  exclusively  for  the 
operation  of  lift-  and  force-pumps,  as  it  is  too  uncertain  in  its 
action  to  work  well  with  centrifugal  pumps  or  mechanical 
elevators. 

The  various  steam  powers  may  be  divided  into  two  gen- 
eral classes,  according  to  the  manner  in  which  they  are  attached 
to  the  pumps.  These  are: 

1.  Direct-acting  steam  pumps. 

2.  Fly-wheel  and  belting  steam  pumps. 

Direct-acting  pumps  have  no  rotary  motion,  their  action 
being  reciprocating,  and  both  steam-  and  water-cylinders  being 
mounted  on  a  solid  bed-plate,  so  that  the  piston-rod  which  pro- 
duces the  power  has  attached  to  it  the  plunger  which  elevates 
the  water.  Fly-wheel  or  indirect- acting  pumps  may  have  the 
motive  power  at  some  distance  from  and  independent  of  the  elevat- 
ing pump,  and  be  connected  therewith  through  shafting  or  belting 
or  some  other  mechanical  device.  They  are  not  so  satisfactory 
or  reliable  in  their  operation  where  used  for  irrigation,  as  they 
are  liable  to  get  out  of  alignment  and  out  of  order,  and  therefore 
require  more  skilled  attendance  than  do  direct-acting  pumps, 
though,  on  the  other  hand,  their  efficiency  is  generally  higher. 

386.  Choice  of  Pumping  Machines. — The  pump  and  mo- 
tive power  which  are  to  be  employed  in  each  particular  case 
depend  wholly  on  the  services  to  be  performed  and  on  various 
local  modifying  conditions.  The  variety  of  pump  must  be 
chosen  according  as  greater  or  less  volumes  are  to  be  elevated 
to  greater  or  less  heights.  The  motive  power  must  be  selected 
according  to  the  pump  chosen,  the  work  to  be  done,  and  the 


CHOICE   OF    PUMPING   MACHINES  513 

fuel  available,  be  this  air,  water  or  wood,  coal,  gasoline  or  elec- 
tricity. Where  means  are  limited  and  the  area  to  be  irrigated  is 
but  a  few  acres,  the  motive  power  chosen  will  usually  be  either 
animal  or  water.  The  first  is  cheapest  of  installation  but  least 
economical,  and  the  second  is  next  cheapest,  where  a  sufficient 
water-supply  is  available  for  the  operation  of  an  ordinary  mid- 
current  undershot  wheel  or  hydraulic  ram.  Where  the  area  is 
small  but  the  means  at  the  disposal  of  the  irrigator  less  limited, 
animal  power  will  usually  be  left  out  of  consideration,  and  the 
choice  rest  between  wind,  water,  hot  air,  gasoline,  alcohol,  electric 
or  steam  pumping-engines.  If  the  wind  be  reasonably  steady 
and  the  facilities  good  for  the  construction  of  a  storage  tank,  that 
power,  though  not  less  expensive  to  install  than  some  others,  is 
least  expensive  and  troublesome  to  maintain  and  operate,  yet  not 
the  most  reliable.  Where  water  is  abundant,  it  furnishes,  through 
rams,  water-wheels,  turbines,  or  water-engines,  the  next  least  ex- 
pensive power  to  maintain  and  operate,  though  not  the  cheapest 
to  install.  The  class  of  water-motor  selected  will  depend  wholly 
upon  the  volume  of  motive  power  available  and  the  height  to 
which  the  water  is  to  be  raised.  Hot-air  engines  and  gasoline- 
engines  furnish  the  most  reliable  power  for  pumping  water,  and 
are  less  difficult  to  operate  than  steam-engines.  Gasoline  or 
alcohol  engines  are  especially  economical  where  coal  or  wood  as 
fuel  are  expensive,  though  hot-air  engines  have  a  wide  adapta- 
bility in  the  variety  of  fuel  which  they  may  utilize.  Steam-engines, 
where  coal  is  cheap,  furnish  the  most  satisfactory  motive  power, 
but  are  generally  not  so  economical  to  operate,  especially  where 
small  areas  are  to  be  irrigated.  For  the  pumping  of  large  vol- 
umes, water  and  steam  are  the  only  competing  motive  powers. 
Where  water  power  is  available  at  some  distance  from  the  wells 
to  be  pumped,  it  can  often  be  converted  into  electricity  and  thus 
be  transported  long  distances  at  relatively  low  cost. 

The  irrigation  engineer  who  proposes  installing  a  pumping 
plant  should  consider  all  the  various  circumstances  which  affect 
the  case  under  consideration.  He  should  carefully  weigh  the 
necessity  for  having  a  permanent  and  steady  supply,  the  inac- 
cessibility of  the  plant  for  repairs  or  replacement  of  broken  parts, 
33 


514  PUMPING,    TOOLS,    AND    MAINTENANCE 

the  relative  cost  and  accessibility  of  different  kinds  of  fuel  or 
of  water,  and  the  degree  of  intelligence  and  skill  possessed  by 
those  who  are  to  operate  the  machine  employed. 

387.  Animal  Motive  Power. — There  are  numerous  modes 
of  utilizing  animal  power  in  pumping  water.  Among  the  oldest 
and  best  known  of  these  are  the  common  domestic  hand  pump, 
the  well-sweep,  and  the  curb  and  bucket,  which  are  all  too  limited 
in  capacity  for  use  in  irrigation.  More  extended  in  use  is  the 
Persian  wheel  and  some  of  its  American  adaptations  which 
have  recently  come  into  use  in  this  country.  There  are  several 
varieties  of  this  apparatus  skilfully  designed  and  constructed 
which  are  more  efficient  than  the  old  Oriental  wheel.  These 
have  large  metal  buckets  hung  on  heavy  linked  chains  which 
revolve  over  the  wheel  and  dip  into  the  source  of  water-supply 
beneath,  and  are  operated  by  iron  cogged  gearing  turned  by 
horses  or  bullocks  attached  to  a  shaft  from  the  center  of  these 
and  walking  around  in  a  circle.  These  have  capacities  varying 
between  500  cubic  feet  per  hour  for  one  horse  up  to  2000  cubic 
feet  per  hour  for  four  horses  for  a  depth  of  20  feet,  the  first  cost 
for  plant  ranging  from  $200  to  $500. 

There  are  on  the  market  a  number  of  mechanical  devices 
for  utilizing  animal  power  in  pumping  water,  consisting  chiefly 
of  various  forms  of  sweeps  to  be  drawn  by  horses  walking  in  a 
circle,  or  treadmills  for  utilizing  horse,  bullock,  or  sheep  power, 
through  gearing  and  shafting.  Most  of  these  are  simple  in 
construction  and  operation,  are  not  liable  to  get  out  of  order, 
and  are  with  their  pump  connection  capable  of  lifting  sufficient 
water  with  a  two-horse  device  to  irrigate  three  to  five  acres  per 
season  without  storage,  while  this  amount  could  be  at  least  doubled 
if  a  storage  tank  of  sufficient  capacity  were  provided  for  retain- 
ing water  raised  during  periods  when  it  is  not  wanted  for  im- 
mediate use. 

Of  the  older  mechanical  devices  for  lifting  water  for  irriga- 
tion there  may  be  enumerated,  as  among  the  more  prominent, 
the  mot  of  India,  which  consists  of  a  rope  passing  over  a  pulley 
down  into  the  well,  and  to  the  end  of  which  a  bucket  or  other 
receptacle  is  attached.  This  is  raised  by  two  bullocks  walking 


WINDMILLS  515 

away  with  the  rope,  usually  down  an  incline,  thus  raising  the 
bucket  to  the  top  of  the  well,  where  it  is  emptied  into  a  distrib- 
uting ditch.  The  Persian  wheel  is  perhaps  the  most  commonly 
employed  of  the  various  devices,  both  in  India  and  generally 
throughout  Asia  and  Egypt.  It  consists  of  a  vertical  wheel 
to  the  outer  rim  of  which  are  either  attached  buckets  which 
dip  into  the  well  or  over  which  is  hung  a  rope  which  hangs  below 
the  lower  periphery  of  the  wheel  and  to  which  buckets  are  at- 
tached, and  as  these  reach  the  upper  circumference  of  the  wheel 
they  spill  their  contents  into  a  trough  which  leads  the  water 
to  the  fields.  Another  old-fashioned  water-lifting  device  is 
the  paecottah  of  India,  which  is  the  sakia  of  Egypt  and  the  bascule 
of  Europe  and  the  common  well-sweep  of  America.  By  its  use 
from  500  to  2000  cubic  feet  of  water  are  raised  in  a  day.  With 
the  mot  two  bullocks  working  10  hours  a  day  will  raise  3}  acre- 
feet  in  a  season  of  90  days.  With  the  Persian  wheel  two  bullocks 
will  lift  2000  cubic  feet  of  water  a  day.  Still  other  devices  of 
this  kind,  and  worked  like  the  well-sweep  by  man  power,  are  the 
latha  or  scoop  of  India  and  China,  the  double-zigzag  balance  of 
Asia  Minor  and  Egypt,  the  well  chain,  the  noria,  the  tympan,  and 
the  Archimedean  screw. 

388.  Windmills. — Windmills  are  being  extensively  used  in 
the  San  Joaquin  valley  in  California,  and  on  the  great  plains 
east  of  the  Rocky  Mountains  and  in  other  portions  of  the  West, 
for  pumping  water  for  irrigation.  They  have  been  most  ex- 
tensively employed  for  pumping  water  for  domestic  use,  but 
as  the  necessity  for  irrigation  has  become  better  appreciated, 
and  as  water  has  become  more  scarce  and  valuable,  .windmills 
have  come  into  more  extended  use  in  providing  water  for  irri- 
gation. The  chief  objection  to  windmills  for  this  purpose  is 
their  unreliability,  as  they  are  wholly  dependent  upon  the  force 
of  the  wind  for  their  operation.  This  objection  is  not  so  seri- 
ous on  the  great  plains  between  the  Rocky  Mountains  and  the 
Mississippi  River,  where  there  is  almost  always  a  sufficiently 
steady  and  powerful  wind  to  keep  mills  constantly  turning.  In 
other  places  they  are  less  certain  in  their  action,  and  may  fail  the 
farmer  at  the  very  time  when  he  is  most  in  need  of  a  water-supply. 


PUMPING,    TOOLS,    AND    MAINTENANCE 


Because  of  their  uncertainty  of  operation,  windmills  should 
never  be  used  for  purposes  of  irrigation  without  providing  as 
an  adjunct  an  ample  tank  or  reservoir  for  the  storage  of  suffi- 
cient water  to  irrigate  a  considerable  area.  As  the  wind  may 
blow  at  any  time  during  the  twenty-four  hours,  and  is  just  as 
likely  to  blow  at  night  as  in  the  day,  when  the  water  cannot 
be  used  in  irrigating  the  fields,  a  storage  capacity  sufficient  cer- 
tainly to  impound  water  pumped  during  the  night-time  should 
be  provided;  though  for  any  security,  and  in  order  to  irrigate  a 
reasonable  area,  ample  capacity  should  be  provided  to  store  the 
water  of  several  days'  pumping  when  irrigation  may  not  be  neces- 
sary. This  storage  capacity  may  be  obtained  by  using  one  of 
the  various  forms  of  elevated  tanks  which  are  supplied  by  wind- 
mill makers;  or,  better  still,  if  the  windmill  can  be  located  at 
a  high  point  on  the  farm,  an  artificial  reservoir  may  be  excavated 
at  this  point  and  suitably  lined,  which  shall  have  capacity  to 
contain  a  much  larger  amount  of  water. 

389.  Capacity  and  Economy  of  Windmills. — The  amount 
of  work  which  a  windmill  will  perform  depends  on  two  prime 
considerations:  (i)  the  force  and  steadiness  of  the  wind,  and 
(2)  the  size  of  the  wind-wheel. 

It  requires  on  an  average  a  wind  velocity  of  not  less  than 
6  miles  an  hour  to  drive  a  windmill,  and  on  an  average  winds 
exceeding  this  velocity  are  to  be  had  during  eight  hours  per  d,ay. 
Hence,  about  two-thirds  of  the  total  wind  movement  is  lost  for 
work.  The  reports  of  the  U.  S.  Weather  Bureau  indicate  that 
the  average  wind  movement  of  the  entire  country  is  5769  miles 

TABLE  XXVI. 

WIND    VELOCITY    AND    POWER. 


Miles  per 
Hour. 

Feet  per 
Second. 

Pressure  per 
Square  Foot, 

Miles  per 
Hour. 

Feet  per 
Second  . 

Pressure  per 
Square  Foot, 

in  Pounds. 

in  Pounds. 

6 

7-5 

.12 

3° 

44-0 

4-4 

10 

14.7 

•5 

35 

5!-3 

6.0 

15 

22.0 

i.i 

40 

58.8 

7-9 

20 

2Q-3 

2.0 

45 

66.0 

10.  0 

25 

36.7 

3-i 

5° 

73-3 

12-3 

CAPACITY   AND   ECONOMY   OF   WINDMILLS 


517 


per  month,  or  about  eight  miles  per  hour.  These  averages  are 
somewhat  exceeded  in  Dakota,  where  the  average  hourly  velocity 
is  ten  miles;  also  in  Nebraska,  Kansas,  and  neighboring  States; 
while  they  are  too  great  for  other  portions  of  the  arid  West.  The 
preceding  table  gives  roughly  the  force  of  the  wind  for  ordinary 
velocities: 

The  following  table  is  derived  from  Mr.  A.  R.  Wolff's  ex- 
cellent work  on  the  windmill,  and  shows  the  capacity  and  econ- 

TABLE  XXVII. 

CAPACITY   OF    WINDMILLS. 


t> 

"O&H 

Revolu- 

Gallons of  Water  Raised  per  Minute  to  an  Elevation  of 

Horse- 

8-3 

££ 
£ 

tions  of 
Wheel. 

Devel- 
oped. 

25  Feet. 

50  Feet. 

75  Feet. 

TOO  Feet. 

150  Feet. 

200  Feet. 

10 

60  to  6<; 

19.2 

9-6 

6.6 

4-7 

0.  12 

12 

55       6° 

33-9 

17.9 

ii.  8 

8-5 

5-7 

.... 

0.21 

14 

5°       55 

45-r 

22.6 

!5-3 

II.  2 

7-8 

4-9 

0.28 

16 

45       5° 

64-6 

31-6 

19-5 

16.1 

9-8 

8.0 

0.41 

18 

40       45 

97-7 

52.2 

32-5 

24.4 

'7-5 

12.2 

0.61 

20 

35       40 

124.9 

63.7 

40.8 

31.2 

19-3 

15.9 

0.78 

25 

30       35 

212.4 

lOJ.O 

71.6 

40.7 

37-3 

26.7 

'-34 

omy  of  an  experimental  windmill  having  various  diameters  of 
wheels,  with  an  assumed  average  velocity  of  wind  of  16  miles 
per  hour  and  with  eight  hours  per  day  as  the  average  number 
of  days  during  which  the  results  given  may  be  obtained. 

Mr.  Wolff  estimates  the  cost  of  operating  a  windmill  for  a 
25-foot  lift,  including  interest  on  first  cost  and  charges  for  main- 
tenance, as  ranging  from  seven-tenths  of  one  cent  per  hour  for 
a  10- foot  wheel  to  24  cents  for  a  1 6-foot  wheel  and  43  cents  for 
a  25-foot  wheel. 

Aside  from  the  uncertainty  of  action  in  windmills,  it  is  evi- 
dent from  the  foregoing  that  the  windmill  is  one  of  the  most 
economical  of  prime  movers.  Its  operation  calls  for  no  expense 
for  fuel,  practically  none  for  attendance  in  self -regulating  mills, 
and  little  or  none  for  repairs.  In  comparison  a  steam-engine  calls 
for  large  expenditures  for  fuel,  repairs,  and  attendance,  while  most 


518  PUMPING,    TOOLS,    AND    MAINTENANCE 

classes  of  water-motors  call  for  heavy  expense  in  providing  and 
maintaining  a  supply  of  water,  as  well  as  for  attendance  and 
repairs.  On  an  average  it  appears  that  the  economy  of  a  wind- 
mill is  at  least  1.5  times  that  of  a  steam-pump,  while  it  has  an 
additional  economy  over  the  latter  because  of  the  attendance 
and  repairs  demanded  by  the  steam-boiler.  On  the  other  hand, 
a  windmill  usually  calls  for  additional  expense  where  it  is  used 
for  irrigation  in  making  its  supply  more  certain  by  providing 
storage  capacity. 

Some  interesting  comparisons  of  the  efficiency  of  various 
windmills  have  recently  been  made  by  Mr.  J.  A.  Griffiths  in 
Australia.  The  mills  experimented  with  were  situated  in  the 
ordinary  manner  directly  over  a  well,  reciprocating  pumps  being 
attached  directly  from  a  crank  on  the  main  axle  of  the  sail-wheel, 
the  latter  being  erected  on  the  usual  wooden  mill-tower.  Mr. 
Griffiths  assumes  the  following  equation  of  energy  required  to 
stop  and  start  a  stream  as  being 


(i) 


in  which  A  is  the  sectional  area  in  square  feet  of  a  stream  of 
air  weighing  W  pounds  per  cubic  foot,  and  moving  with  a  uni- 
form velocity  of  v  feet  per  second.  In  computing  the  efficiency 
of  windmills  the  unit  adopted  is  usually  100  square  feet  cor- 
responding to  a  circle  of  11.3  feet  diameter,  or  about  that  of 
the  smallest  windmills  ordinarily  employed,  and  the  unit  of 
velocity  is  10  miles  per  hour.  A  uniform  stream  of  air  of  100 
square  feet  sectional  area,  weighing  .075  pound  per  cubic  foot 
and  moving  with  a  velocity  of  10  miles  per  hour,  contains  an 
actual  kinetic  energy  of  1,323,267  foot-pounds  per  hour,  or  .6683 
of  an  English  horse-power,  and  from  this  coefficient  the  energy 
of  any  other  stream  may  be  calculated.  In  the  following  table 
are  given  horse-powers  of  wind  acting  upon  an  area  of  100  square 
feet  for  velocities  ranging  from  5  to  30  miles  an  hour. 

The  highest  net  efficiency  observed  in  Mr.  Griffiths'  experi- 
ments at  7  miles  per  hour  was  twenty-five  per  cent;  also,  that 
the  velocity  of  the  wind  when  leaving  the  mill  was  '.909  of  the 


VARIETIES    OF    WINDMILLS 


5*9 


approaching  velocity.  He  further  observed  that  the  loss  of  ve- 
locity was  proportionately  less  than  the  loss  of  energy,  and  that 
with  a  working  efficiency  of  10  per  cent  or  less  the  loss  of  velocity 
was  scarcely  appreciable. 

TABLE  XXVIII. 

ENERGY  OF  WIND  ACTING  UPON  A  SURFACE  OF  IOO  SQUARE  FEET. 


VeS.°f                     AtSea-,.vel. 

At  1000  Feet  above 
Sea-level. 

At  2000  Feet  above 
Sea-level. 

Miles  per  Hour. 

H.-P. 

H.-P. 

H.-P. 

^ 

o.o83S 

0.0780 

0.0724 

10 

0.6683 

0.6237 

0.5792 

15 

2-2550 

2.1050 

1-9550 

20 

5-3470 

4.9900 

4.6340 

25 

10.4400 

9-7460 

9.0^00 

30 

18.0400 

16.8400 

15.6400 

In  designing  a  windmill  for  pumping,  two  things  have  to 
be  considered — the  torque,  or  statical  turning  moment,  and  the 
speed  of  the  wheel  in  relation  to  that  of  the  pump.  The  for- 
mer should  be  as  large  as  possible  so  that  the  mill  will  start  with 
the  faintest  wind,  and  the  latter  must  not  be  too  fast  for  the 
pumps  in  a  small  mill  or  too  slow  in  a  large  one.  Hence  the 
size  of  a  mill  is  an  important  element  in  the  arrangement  of  its 
vanes.  The  angle  between  any  portion  of  a  vane  and  the  plane 
of  the  wheel  is  termed  the  weather  angle,  and  to  obtain  the  greatest 
torque  at  starting  the  weather  angle  should  be  the  complement 
of  the  best  incidence  angles,  or  between  70  and  55  degrees.  In 
practice  it  is  found  that  the  weather  angle  is  never  as  great  as 
this,  being  in  the  best  examples  about  43  degrees. 

The  following  table  gives  the  results  of  Mr.  Griffiths1  ex- 
periments for  the  five  American-made  windmills  tested. 

390.  Varieties  of  Windmills. — A  wind-wheel  is  designed 
for  the  utilization  of  wind-power  much  as  is  a  water-wheel  for 
that  of  water-power,  but  differs  from  it  in  that  the  former  is 
wholly  immersed  in  a  sea  of  air  while  the  latter  is  acted  upon 
by  a  limited  current  of  water.  The  common  paddle-wheel 
will  not  be  revolved  by  the  wind,  because  its  force  is  exerted 
equally  on  diagonally  opposite  paddles;  hence  the  paddles  on 


520 


PUMPING,    TOOLS,    AND  MAINTENANCE 


X 


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AT  MAXIMUM  EFFICIENCY. 

Velocity  of  wind,  miles  per  hour  
Velocity  of  mill,  revolutions  per  minute  
Actual  horse-power  

Horse-power  per  100  square  feet  of  gross  a 
Maximum  net  efficiency,  per  cent  

IN  100  AVERAGE  HOURS,  CALM  LOC 

Average  quantity  of  water  lifted,  gallons  pe 
Average  continuous  horse-power  developed 
Average  continuous  gross  horse-power  deve 
Average  net  efficiency,  per  cent  

IN  100  AVERAGE  HOURS,  WINDY  LO 

Average  quantity  of  water  lifted,  gallons  p< 
Average  continuous  horse-power  developed 
Average  continuous  gross  horse-power  devt 
Average  net  efficiencv,  per  cent  

VARIETIES    OF    WINDMILLS  521 

one  side  only  should  be  exposed  to  the  wind — a  result  which  is 
obtained  without  the  use  of  a  screen  by  pivoting  the  paddles 
upon  their  axis  so  that  on  one  side  they  present  a  broad  face 
to  the  wind  and  in  passing  to  the  other  side  they  turn  on  their 
pivots  so  as  to  present  a  feather  edge  to  the  wind. 

Windmills  consist  of  arms,  cross-bars,  and  clothing  therefor. 
They  are  made  plane,  warped,  or  concave.  The  older  type  of 
sail-mill  is  common  in  Europe,  especially  Holland,  and  has 
usually  four  arms,  occasionally  more.  The  narrow  part  of  the 
sail  is  usually  covered  with  a  wind-board,  as  it  is  called,  and 
the  broader  with  wind  slats  of  wood  or  with  a  covering  of  sail- 
cloth. American  mills  differ  from  European  mills  in  that  they 
are  chiefly  of  the  propeller  type,  and  instead  of  a  small  number 
of  sails  of  considerable  width  are  made  with  a  great  number  of 
blades  or  slats  of  slight  widths,  and  otherwise  have  an  entirely 
distinct  appearance  from  the  European  mill,  as  the  wheel  pre- 
sents a  closed  surface  as  compared  with  the  large  open  spaces 
between  the  arms  of  the  sail-mill.  As  a  result  of  this  mode  of 
construction  the  American  mill  is  lighter  in  weight  as  well  as 
appearance  than  the  European  mill;  and  though  the  wide  angle 
of  the  vane  is  not  as  advantageous  as  in  the  sail-mill,  the  sur- 
face presented  for  a  given  diameter  is  sufficiently  great  to  more 
than  compensate  for  this  difference,  and  it  would  appear  that 
the  American  mill  is  superior  to  the  European  type  from  the 
fact  that  it  is  rapidly  replacing  them  in  Europe. 

The  several  types  of  American  mills  are  distinguished  both 
by  the  form  of  the  wheel  and  the  mode  of  regulating  or  gov- 
erning its  position  and  direction  so  as  to  obtain  a  uniform  power 
and  rate  of  revolution  under  varying  wind  velocities.  There 
are  two  principal  types  of  these  mills,  namely,  (i)  sectional  wheels 
with  centrifugal  governor  and  independent  rudder,  and  (2)  solid 
wheels  with  side-vane  governor  and  independent  rudder.  Be- 
sides these  there  are  a  number  of  special  types,  including  various 
combinations  of  solid  and  sectional  wheels  with  various  arrange- 
ments of  rudder,  or  in  some  cases  no  rudder  is  employed,  and 
the  wind  pressure  upon  the  wheel  is  relied  on  to  bring  it  into 
direction. 


522  PUMPING,    TOOLS,    AND   MAINTENANCE 

The  windmill  is  usually  placed  directly  over  the  well  on  a 
wooden  or  iron  tower  or  scaffolding,  having  usually  four  upright 
inclined  pillars  which  straddle  the  well.  This  tower  should  be 
sufficiently  high  to  raise  the  wheel  at  least  20  feet  above  all  ob- 
structions, as  buildings,  trees,  etc.  This  may  require  a  tower, 
preferably  of  steel;  50  to  70  feet  high.  A  small  wheel  on  a  high 
tower  is  better  than  a  large  wheel  on  a  low  tower.  At  the  top  of 
the  scaffolding  is  a  platform  or  a  turntable  with  an  open  center, 
through  which  the  pump-rod  descends  vertically  to  a  recipro- 
cating force-pump  in  the  well.  A  horizontal  crank-shaft  sup- 
ported in  bearings  on  the  upper  movable  part  of  the  turntable 
is  connected  with  the  pump  by  a  swivel- joint  in  order  to  permit 
of  the  rotation  of  the  mill  top  necessary  in  adjusting  the  sails 
to  the  various  horizontal  directions  of  the  wind.  An  overhang- 
ing end  of  the  crank-shaft  carries  the  wind-wheel,  which  in  some 
forms  is  on  the  lee  side  of  the  tower,  in  which  case  it  maintains 
its  direction  perpendicular  to  the  wind  by  pulling  the  turntable 
around,  and  is  rudderless.  In  others  the  pressure  of  the  wind 
on  a  rudder  vane  with  sufficient  area  and  leverage  to  overbalance 
the  wind  keeps  it  perpendicular  to  the  wind,  and  on  the  wind- 
ward side  of  the  tower.  In  addition  there  is  also  a  controlling 
or  regulating  gear  to  stop  the  mill  when  the  reservoir  is  full  or 
repairs  are  necessary,  and  to  prevent  damages  by  gales.  This 
gear  is  operated  by  hand  or  is  automatic. 

Of  side-vane  governor  mills  the  Corcoran  and  Eclipse  are 
excellent  examples.  Of  centrifugal  governor  mills  the  Halla- 
day  and  Althouse  are  good  examples.  The  latter  is  folding 
and  rudderless.  Of  special  mills  the  Buchanan  is  a  good  ex- 
ampb,  being  dependent  for  its  regulation  on  the  tendency  of 
the  wheel  to  go  into  the  direction  it  turns  as  the  velocity  of  the 
wind  increases.  The  Stover  is  a  solid  sail-wheel  with  vanes 
so  regulated  that  the  mill  may  be  reefed  or  even  stopped  or  other- 
wise regulated  to  go  slowly  in  heavy  winds.  The  Perkins  mill 
has  a  solid  wheel  with  automatic  rudder,  which  also  acts  as  an 
automatic  regulator,  though  in  slow  winds  it  must  be  half  reefed. 
The  Carlyle  special  mill  has  a  rudder  arranged  to  reef  the  sail 
in  storms,  and  so  attached  by  an  adjustable  cam  as  to  cause 


VALUE    OF    WINDMILLS    AS    IRRIGATING    MACHINES        523 

the  center  of  gravity  of  the  rudder  to  rise  as  it  falls  toward  the 
wheel.  The  Leffel  windmill  depends  for  regulation  on  the  fact 
that  the  center  line  of  the  wheel  shaft  stands  off  from  and  parallel 
to  the  plane  of  the  rudder,  while  the  wheel  of  the  mill  is  of  peculiar 
type,  being  made  of  metal  blades  with  a  helical  curve.  The 
Aermotor  Cyclone  and  Woodmonse  are  excellent  types  of  modern 
American  mills.  The  Advance  is  a  good  type  of  automatic 
regulating  rudder  mill  having  both  side  steering-vane  and  govern- 
ing rudder. 

391.  Value  of  Windmills  as  Irrigating  Machines. — Wind- 
mills average  in  cost  from  $50  to  $400,  according  to  size  and 
make.  Any  one  intending  to  use  a  mill  should  purchase  it  from 
a  reliable  maker,  and  choose  a  design  according  to  the  work 
which  the  mill  is  expected  to  perform  and  the  average  wind  veloc- 
ity in  his  locality.  Thus,  on  the  Rocky  Mountain  plains  a  wind- 
mill will  run  at  least  twelve  hours  in  a  day,  while  in  some  of  the 
mountain  valleys  between  the  Rocky  Mountains  and  the  Pacific 
slope  eight  hours  per  day  is  an  average  run.  Experience  with 
average  mills  already  constructed  shows  that  a  5-inch  pump 
will  discharge  about  250  cubic  feet  an  hour,  a  6-inch  pump  about 
380  cubic  feet  per  hour,  and  an  8-inch  pump  about  650  cubic 
feet  per  hour.  On  the  average  basis  of  duty  of  water  a  5 -inch 
pump  will  therefore  irrigate  about  6  acres  if  running  constantly 
or  about  2  acres  if  running  one-third  of  the  time. 

Recent  experiments  by  Prof.  E.  C.  Murphy  show  that  the 
power  of  windmills  does  not  increase  much  faster  than  the  square 
of  the  wind  velocity,  and  about  as  i|  times  the  diameter  of  the 
wind-wheel.  A  good  1 2-foot  steel  mill  should  furnish  i  horse- 
power in  a  2o-mile  wind  and  1.4  horse-power  in  a  25-mile  wind. 
A  1 6-foot  mill  will  furnish  1.5  horse-power  in  a  20- mile  wind 
and  2.3  horse-power  in  a  25-mile  wind. 

The  average  mill  will,  according  to  experience,  do  sufficient 
work  to  irrigate  from  i  to  3  acres.  If,  however,  a  storage  reser- 
voir or  tank  be  supplied  this  may  be  emptied  and  filled  several 
times  during  an  irrigating  season,  which  contains  several  irri- 
gating periods,  and  a  mill  supplied  with  such  a  reservoir  may 
therefore  irrigate  from  three  to  five  times  the  area  above  indicated. 


524  PUMPING,    TOOLS,    AND    MAINTENANCE 

There  are  numerous  windmills  in  the  West  which  irrigate  from 
10  to  15  acres  from  wells  30  to  150  feet  in  depth  with  the  aid  of 
storage  tanks,  and  these  plants,  including  mill  and  tank,  average 
in  cost  from  $150  to  $350.  Taking  $250  as  a  mean  and  their 
capacities  at  12%  acres,  the  cost  of  these  plants  is  about  $20  per  acre 
irrigated  and  the  cost  for  maintenance  practically  nil.  A  2  5  -foot 
mill  will,  according  to  Table  XXVII,  in  a  working  day  of  8  hours, 
pump  one-third  of  an  acre-foot  to  a  height  of  25  feet,  or  one-sixth 
of  an  acre-foot  to  a  height  of  50  feet.  In  an  irrigating  season  of 
120  days  it  will  raise  40  acre-feet  to  the  lower  elevation,  and  were 
storage  provided  for  half  this  volume  and  the  reservoir  filled  before 
the  beginning  of  the  irrigating  season,  such  a  mill  would  theo- 
retically, under  average  wind  conditions,  be  capable  of  furnish- 
ing enough  water  to  irrigate  from  20  to  30  acres.  It  is  doubt- 
ful, however,  if  such  a  duty  will  be  practically  obtained  even  with 
the  most  ample  storage  facilities. 

392.  Power  in  Falling  Water.  —  Water  acts  as  a  motive  power 
by  its  weight  or  by  its  impulse.  In  the  former  case  it  falls  slowly 
through  a  given  height,  and  in  the  latter  it  passes  through  a 
machine  with  a  constantly  decreasing  velocity.  The  work  P 
which  it  performs  because  of  a  given  fall  h  is 

P  =  Qwh,       ......     (2) 

in  which  Q  is  the  whole  quantity  of  water  falling  in  one  second 
of  time  and  w  the  weight  of  a  unit  of  volume.  If  v  is  the  velocity 
with  which  it  enters,  then  the  work  which  it  performs  because 
of  impulse,  before  coming  to  rest,  is 


but  water  started  from  rest  will  attain  a  velocity  v  only  after  it 

v2 
has  passed  through  a  height  h  =  —  ;    hence  in  the  latter  case 

the  formula  may  be  written  as  is  (2). 

The  following  simple  graphic  mode  of  determining  the  horse- 
power which  is  contained  in  any  given  waterfall  was  published 
by  Prof.  Olin  H.  Landreth  in  Engineering  News.  It  is  based 


POWER    IN    FALLING    WATER 


525 


on  the  formula  HP  = 


Hqwe 
500 


,  in  which  H  is  the  effective  head  on 


the  wheel  in  feet,  q  the  quantity  of  water  in  cubic  feet  per  second, 
•w  the  weight  of  water  per  cubic  foot,  and  e  the  percentage  of 
efficiency  of  the  wheel.  For  w  =  62.4  Ibs.;  HP  =  o.n^^Hqe. 

The  inclined  lines  radiating  from  the  zero  at  the  lower  left 
corner  are  of  three  different  kinds:  Those  running  to  the  upper 
edge  of  the  diagram  represent  the  quantity  of  water;  those  run- 
ning to  the  right  side  of  the  diagram  represent  the  different  per- 
centages of  efficiency,  except  the  one  line  which  crosses  the  margin 

Water,  Cu.  ft.  per.  Sec. 
30  30          40  60          «0 


30  40  60 

Horse  Power 


FIG.  191. — Diagram  for  Determining  Horse-power  of  Water-wheels  and 

Water-falls. 

Example:  Head  =  15.6  ft.     Quantity  =  40  cu.  ft.  per  sec.     Efficiency  =  75%- 
Then  Horse-power  =  53-2. 

between  85%  and  90%,  which  is  a  conversion  line  to  transform 
the  resulting  value  of  the  horse-power  into  such  linear  values  as  to 
permit  them  to  be  represented  by  the  graduations  along  the  base 
of  the  diagram.  This  line  is  drawn  at  an  angle  with  the  vertical 
lines,  whose  tangent  t  =  \  (0.1134)  75.^)^,  where  v  and  h  are 


526  PUMPING,    TOOLS,    AND   MAINTENANCE 

the  numerical  values  of  the  vertical  scale  of  head  and  the  hori- 
zontal scale  of  quantity,  the  J  being  introduced  in  this  case  to 
make  the  HP  units  along  the  base  of  the  diagram  one-half  the 
value  of  the  quantity  units  along  the  top  edge  of  the  diagram. 
To  use  the  diagram:  Start  with  the  value  of  the  head  on  the 
left  margin,  pass  horizontally  to  the  radiating  line  representing 
the  given  quantity,  thence  pass  vertically  down  to  the  proper 
efficiency  line,  thence  pass  horizontally  to  the  inclined  conversion 
line,  thence  vertically  down  to  the  horse-power  line  along  the 
base  of  the  diagram,  where  the  proper  value  may  be  read  off. 
With  heads  or  quantities  in  excess  of  the  maximum  value  of 
the  diagram,  the  scales  may  be  assumed  changed  to  ten  times 
that  graduated  and  the  resulting  horse-power  read  off  to  a  scale 
either  ten  or  one  hundred  times  that  graduated,  according  to 
whether  one  or  both  the  argument  scales  have  been  amplified, 
one  or  two  other  arrangements  of  the  lines  indicating  respec- 
tively the  heads. 

393.  Water-motors. — Hydraulic  motors  are  machines  de- 
signed to  utilize  the  energy  possessed  by  falling  or  moving  masses 
of  water,  and  may  be  divided  into  the  following  two  classes: 
(i)  water-wheels  and  (2)  water-engines.  These  may  be  again 
divided  into  several  classes,  in  some  of  which  both  water-wheels 
and  water-engines  act  either  through  power  due  to  fall  or  due  to 
impulse,  or  a  combination  of  both.  Water-wheels  may  be  sub- 
divided into  two  classes:  (i)  vertical  water-wheels  and  (2) 
horizontal  water-wheels.  Of  the  former  we  have  the  more  com- 
mon of  the  old-fashioned  wheels: 

1.  Undershot  water-wheels. 

2.  Breast- wheels. 

3.  Overshot  water-wheels. 

4.  Hurdy-gurdies. 

5.  Pelton  water-wheels. 

The  latter  is  a  modern  adaptation  of  the  old-fashioned  hurdy- 
gurdy,  and  is  properly  an  impulse  wheel.  Horizontal  wheels 
are  turbines  of  vorious  types,  and  in  these,  like  vertical  wheels, 
water  may  act  both  by  pressure  or  -impulse,  or  by  a  combina- 
tion of  the  two. 


UNDERSHOT   WATER-WHEELS  527 

Water-engines  may  be  divided  into  three  classes' 

1.  Bucket-engines. 

2.  Rams. 

3.  Water- pressure  engines. 

The  first  is  an  antiquated  form  of  motor  by  which  work  is 
performed  by  allowing  water  to  enter  buckets,  thus  causing 
these  to  descend  vertically.  Rams  utilize  the  impulse  due  to 
the  weight  of  a  large  body  of  water  in  forcing  a  smaller  body 
to  a  desired  height.  Water-pressure  engines  utilize  the  fluid 
properties  of  water  in  a  manner  somewhat  resembling  the  opera- 
tion of  steam-engines — producing  a  reciprocal  motion  through 
the  pressure  of  water  confined  in  an  upright  pipe. 

Assuming  one  has  to  elevate  a  given  quantity  of  water  to  a 
fixed  height,  having  at  one's  disposal  a  hydraulic  force  which 
it  is  desired  to  apply  to  the  work,  we  may  divide  the  problem 
into  two  parts:  (i)  The  fall  may  be  distinct  from  the  water  which 
is  to  be  lifted,  or  (2)  the  question  of  fall  may  be  inseparable  from 
the  water  to  be  elevated.  In  the  first  class  are  included  all  water- 
wheels  and  bucket-engines;  in  the  second  are  included  rams 
and  most  forms  of  water-pressure  engines.  In  either  case  it 
may  be  necessary  to  raise  a  large  volume  to  a  small  height  or  a 
small  volume  to  a  large  height,  and  each  of  these  offices  may  be 
performed  through  a  large  volume  of  power  from  a  small  height, 
or  a  small  volume  of  power  from  a  great  height.  It  is  this  intimate 
connection  between  volume  and  head  of  power  and  of  resulting 
work  which  calls  for  the  exercise  of  ingenuity  and  discretion 
on  the  part  of  the  engineer  in  choosing  the  water-motor  by  which 
this  work  is  to  be  done.  Thus  a  ram  is  nearly  always  called 
upon  to  utilize  a  large  volume  of  power  from  a  small  height  to 
raise  a  small  volume  of  water  to  a  great  height.  The  Pelton 
water-wheel  generally  utilizes  a  small  volume  of  power  from  a 
great  height  to  elevate  varying  quantities  of  water  to  varying 
heights. 

394.  Undershot  Water-wheels. — The  word  water-wheel  is 
usually  applied  to  the  various  old-fashioned  vertical  wheels, 
undershot,  breast,  and  overshot  wheels.  Undershot  wheels 
may  be  classified  as  midstream  wheels,  the  common  undershot 


528  PUMPING,    TOOLS,    AND   MAINTENANCE 

wheels,  and  Poncelet  wheels.  In  midstream  wheels  the  motive 
power  is  due  to  the  velocity  or  impulse  of  the  current  of  water 
in  the  stream  in  which  the  wheel  is  set,  and  such  wheels  are  em- 
ployed almost  exclusively  for  the  elevation  of  water  for  irriga- 
tion. They  are  very  simple  in  construction  and  operation, 
and  may  be  advantageously  employed  where  water  is  abundant, 
even  in  streams  having  the  very  slowest  velocity  of  flow. 

Midstream  wheels  produce  the  greatest  power  for  the  smallest 
diameter  of  wheel  when  the  float-boards  are  made  straight, 
but  not  radial.  They  vary  from  12  to  16  feet  in  diameter,  but 
are  not  infrequently  larger,  the  float-boards  varying  from  9  to 
12  in  number,  while  two  of  them  at  least  should  always  be  im- 
mersed at  the  same  time.  These  float-boards  project  from  24 
to  30  inches  from  the  wheel-rim,  and  dip  into  the  water  about 
half  of  their  depth.  In  rivers  where  the  water-level  fluctuates, 
the  axle  of  the  wheel  is  made  movable  on  its  supports  to  render 
it  capable  of  being  raised  or  lowered  at  pleasure  to  suit  the  height 
of  water-level,  and  this  is  effected  by  resting  one  or  both  ex- 
tremities of  the  axle  on  floats.  The  horse-power  of  a  midstream 
wheel  may  be  calculated  by  the  following  formula  from  Mr.  P.  R. 
B  jorling ; 

HP  =  (v  —  vj  .0028 A  v, (4) 

in  which  v  is  the  velocity  of  the  stream  in  feet  per  second,  v^ 
the  mean  velocity  of  the  float-boards  in  feet  per  second,  and  A 
the  immersed  area  of  the  float-boards  in  square  feet. 

Numerous  wheels  of  this  class  have  been  successfully  em- 
ployed in  pumping  water  for  irrigation  in  various  portions  of 
the  West.  In  some  cases  these  wheels  have  attached  to  their 
outer  rim  a  row  of  buckets  (Fig.  173),  which  dip  into  the  water 
as  the  wheel  revolves,  are  thus  filled,  and  then  as  they  reach 
the  upper  portion  of  their  revolution  spill  their  contents  into  a 
trough  which  leads  to  the  irrigating  ditches.  Such  wheels  are 
called  norias,  and  are  of  very  ancient  origin,  having  been  used 
for  ages  in  all  portions  of  the  world  most  extensively,  perhaps, 
in  Egypt  and  Italy.  At  other  times  midstream  wheels  are  sus- 
pended directly  in  the  stream  current,  and  by  means  of  gearing 


UNDERSHOT   WATER-WHEELS 


529 


or  belting  are  connected  with  pumps  which  elevate  the  water 
for  irrigation.  Such  contrivances  have  been  employed  in  the 
West,  one  of  which,  on  the  Platte  River,  has  a  lo-foot  wheel, 
14  feet  broad  on  the  face.  It  runs  a  3J-inch  centrifugal  pump, 
and  is  said  to  elevate  2\  second-feet  of  water  to  a  height  of  16 
feet,  or  5  acre-feet  per  twenty-four  hours. 


FI 


2.  —  Undershot  Water-wheel  or  Noria. 


The  average  diameter  of  the  midstream  water-wheel  of  the 
West  varies  from  10  to  20  feet  and  the  length  of  the  blade  of 
the  paddle  is  from  6  to  10  feet.  Some  wheels  of  this  variety  but 
of  large  size  have  been  successfully  employed  —  notably  on  the 
Green  River  in  Colorado  —  which  are  from  20  to  30  feet  in  diam- 
eter. These  are  hung  on  wooden  axles  5  inches  in  diameter, 
while  their  paddles  dip  2  feet  into  the  stream.  They  are  used  as 
norias,  for  on  their  outer  circumference  are  buckets  of  wood  hav- 
ing an  air-hole  in  the  bottom  closed  by  a  suitable  leather  flap-valve 
which  permits  the  bucket  to  fill  rapidly  by  forcing  out  the  air. 
These  buckets  are  6  feet  in  length  and  4  inches  square,  and  have 

34 


530  PUMPING,    TOOLS,    AND    MAINTENANCE 

a  capacity  of  a  little  less  than  a  cubic  foot  each.  The  largest 
of  the  wheels  on  the  Green  River  have  16  paddles  and  lift  10 
cubic  feet  of  water  per  revolution,  and  as  they  make  two  revolu- 
tions a  minute,  though  they  spill  a  large  portion  of  their  contents, 
each  wheel  handles  about  4000  cubic  feet  per  day,  or  approxi- 
mately TO"  of  an  acre-foot. 

Common  undershot  water-wheels,  as  distinguished  from  mid- 
stream wheels,  are  the  best  where  a  fall  of  convenient  height 
cannot  be  obtained,  and  the  velocity  of  the  water  is  yet  relatively 
great.  These  are  confined  in  a  channel  which  is  made  about  the 
width  of  the  wheel  and  is  wider  at  the  inlet  than  at  the  wheel  so 
as  to  give  freedom  of  access  to  the  water  and  to  increase  its  velocity. 
These  wheels  operate  most  satisfactorily  where  the  fall  is  from 
-|-  to  2  feet  in  the  course  of  the  race.  The  paddles  are  similar 
to  those  for  midstream  wheels,  though  sometimes  they  are  curved 
and  of  iron.  The  number  of  float-boards  or  paddles  for  such 
a  wheel  may  be  determined  by  the  formula 

dd 

n  =  -—  +  12, (5) 

o 

in  which  n  is  the  number  of  float-boards  and  d  the  diameter  of 
the  wheel.  These  wheels  vary  in  diameter  from  10  to  20  feet, 
and  are  usually  constructed  of  from  30  to  40  paddles,  varying 
from  ij  to  2j  feet  in  depth,  their  length  being  from  3  to  6  feet. 
The  power  developed  by  such  a  wheel  may  be  ascertained  by 
the  formula 

HP  =  .ooo6qh (6) 

in  which  is  the  quantity  of  water  in  cubic  feet  per  minute  and 
h  the  head  of  water  in  feet. 

Poncelet  wheels  act  rather  on  the  turbine  principle,  their 
paddles  being  curved.  They  are  usually  immersed  to  the  height 
of  their  axes,  and  the  water  is  screened  from  them  with  the  ex- 
ception of  a  few  inches  near  their  under  surface,  so  that  it  im- 
pinges by  impulse  against  the  under  side  of  the  wheel  and  acts 
much  as  does  a  turbine.  The  power  they  are  capable  of  generat- 
ing may  be  expressed  by  the  formula 

HP  =  .o6Sqh .      (7) 


OVERSHOT   WATER-WHEELS  531 

Breast-wheels  are  placed  where  there  is  a  considerable  fall 
in  a  manner  similar  to  Poncelet  wheels,  so  that  the  level  of  water 
is  about  at  the  height  of  their  axes.  They  have  usually  curved 
paddles  or  buckets,  and  the  water  impinges  against  them  both 
by  weight  and  impulse  at  a  point  just  below  the  axial  line. 

395.  Overshot  Water-wheels. — Overshot  wheels  are  more 
economical  in  their  use  of  water,  and  are  therefore  employed 
where  water  is  scarce.  In  these  the  water  is  delivered  above 
the  wheel  by  means  of  a  flume,  race,  or  penstock,  and  they  are 
so  constructed  that  the  water  may  be  delivered  either  on  the 
near  or  the  far  side  of  the  wheel,  according  to  the  arrangement 
of  the  outlet  gates  controlling  the  supply.  On  the  outer  cir- 
cumference of  the  overshot  wheel  is  a  series  of  buckets  into  which 
the  water  pours  and  by  its  weight  causes  the  wheel  to  revolve. 
As  the  wheel  turns  each  bucket  fills  as  it  passes  the  inlet  orifice 
and  empties  as  it  approaches  the  bottom,  so  that  on  one  side 
are  always  a  certain  number  of  buckets  filled  with  water.  This 
class  of  wheels  may  be  employed  in  falls  of  from  6  to  60  feet, 
and  with  streams  having  from  a  few  up  to  50  second-feet  dis- 
charge. In  order  to  lose  as  little  of  the  fall  as  possible  the  bot- 
tom of  the  wheel  should  approach  close  to  the  lower  water  sur- 
face, but  should  not  dip  into  it,  as  by  drowning  the  wheel  its 
power  is  diminished.  These  wheels  are  made  of  such  width 
as  to  permit  of  their  buckets  being  large  enough  to  hold  a  con- 
siderable weight  of  water. 

The  buckets  of  overshot  wheels  may  be  made  of  straight 
boards  or  sheets  of  metal  having  two  or  three  bends  in  them,  or 
may  be  curved.  The  number  of  buckets  may  be  calculated  by 
the  following  formulas  given  by  Bjorling:  For  wheels  from 
12  to  20  feet  in  diameter, 

n  =  2.id: (8) 

and  for  wheels  25  to  40  feet  in  diameter, 

n  =  2.3<*.      .      .      .t     .     .      .      .     (9) 

The  depth  of  shrouding  for  these  wheels  is  about  12  inches,  and 
the  bucket  opening  is  about  J  of  a  square  foot  for  each  cubic 
foot  of  bucket  contents,  or  is  about  7  inches  in  width.  The 


532  PUMPING,    TOOLS,    AND   MAINTENANCE 

quantity  of  water  in  cubic  feet  per  second  being  Q,  the  effective 
horse-power  of  such  a  wheel  may  be  gotten  by  the  formula 

HP  =  .oSsQh (10) 

Overshot  water-wheels  may  be  employed  to  operate  through 
gearing  or  belting  any  of  the  usual  forms  of  reciprocating  or 
centrifugal  pumps,  and  will  elevate  volumes  of  water  to  heights 
proportioned  to  the  power  they  are  capable  of  developing. 

396.  Turbine  Water-wheels. — Turbine  wheels  may  be  di- 
vided into  three  classes,  according  as  they  are  acted  on  (i) 
through  impulse,  (2)  through  pressure,  and  (3)  through  reaction. 
Impulse  wheels  have  plain  or  concave  vanes  or  float-boards,  on 
which  the  water  strikes  more  or  less  perpendicularly.  Pressure- 
wheels  have  curved  float-boards  along  which  the  water  glides. 
Reaction  wheels  consist  of  an  arrangement  of  pipes  from  which 
water  issues  tangentially.  To  this  latter  class  really  belong 
Pelton  wheels,  which  are  vertical  reaction  wheels. 

While  pressure  and  reaction  wheels  are  similar  in  construc- 
tion, they  differ  in  that  in  the  former  the  passages  between  the 
vanes  are  not  completely  filled  with  water,  while  in  reaction 
wheels  the  water  fills  and  flows  through  the  whole  section  of  the 
discharge-pipe.  In  impulse  wheels  the  water  spreads  over  the 
vanes  in  all  directions,  while  in  pressure  and  reaction  wheels  it 
flows  only  over  one  side.  Turbines  are  again  distinguished  as 
(i)  outward-,  (2)  inward-,  and  (3)  mixed-  or  parallel-flow  turbines. 
The  former  receive  the  water  at  the  center  and  deliver  it  at  the 
periphery  of  the  revolving  wheel,  the  regulating  apparatus  con- 
sisting of  a  ring  inserted  between  the  outer  periphery  of  the 
guide-blades  and  the  internal  periphery  of  the  revolving  wheel. 
In  inward-flow  turbines  the  motion  of  the  water,  as  the  name 
implies,  is  practically  the  reverse  of  that  for  outward  flow.  Tur- 
bines possess  an  advantage  over  vertical  water-wheels  in  that 
they  may  be  used  with  any  fall  of  water  from  one  foot  to  several 
hundred  feet.  The.  efficiency  of  turbines  differs  with  the  height 
of  the  fall.  It  is  less  for  small  wheels  and  high  falls  and  greater 
for  large  wheels  and  small  falls.  Overshot  wheels  frequently 
attain  a  greater  efficiency  than  turbines  with  falls  of  20  to  40 


TURBINE   WATER-WHEELS  533 

feet,  while  with  falls  of  10  to  20  feet  their  power  is  about  the 
same;  but  turbines  possess  a  great  advantage  over  other  (except 
Pelton)  water-wheels  in  having  the  same  efficiency  under  dif- 
ferent falls  and  volumes,  and  in  that  they  can  be  regulated.  Some- 
times the  whole  power  may  be  required  of  the  turbines,  at  other 
times  only  a  part  may  be  required;  sometimes  water  is  scarce, 
and  at  other  times  abundant;  but  the  regulating  apparatus  is 
such  that  the  efficiency  remains  nearly  the  same.  The  chief 
differences  between  turbines  and  vertical  water-wheels  are  that 
the  turbines  may  be  drowned,  but  vertical  wheels  must  be  elevated 
above  the  water  in  the  tail-race;  the  turbine  takes  its  supply  at 
the  bottom  of  the  fall  and  the  water-wheel  at  the  top  or  beginning 
of  the  fall,  and  therefore  the  former  obtains  nearly  the  whole 
pressure  due  to  the  head  or  height  of  the  fall;  turbines  work 
without  material  loss  of  energy  when  drowned  and  move  with  a 
greater  velocity  than  vertical  water-wheels,  and  hence  may  be 
reduced  in  size  and  weight  for  equal  power. 

The  outward-flow  turbine  is  more  popular  in  Europe,  and  is 
generally  known  as  the  Fourneyron  type  of  turbine.  The  horse- 
power of  this  class  of  turbine  may  be  roughly  determined  by 
the  formula 

»•-£  .......  <"> 

in  which  q  is  the  quantity  of  water  flowing  through  the  pipes  of 
the  turbine  per  minute.  Inward-flow  turbines  are  more  popu- 
lar in  the  United  States.  They  are  the  reverse  of  the  Four- 
neyron type  in  that  the  guide-  wheel  surrounds  the  revolving 
wheels  and  after  the  water  has  passed  the  buckets  it  is  gradu- 
ally deflected  downward  by  the  curved  under  side  of  the  re- 
volving wheel.  Mixed-  and  parallel-flow  turbines  are  gener- 
ally known  as  the  Jonval  or  Girard  type  of  turbine.  They  may 
be  fixed  at  any  convenient  distance  above  the  tail-race,  and 
must  have  sufficient  water  above  the  guide-blades  to  allow  it 
to  enter  freely  without  eddies.  The  horse-power  of  this  type 
of  turbine  may  be  roughly  determined  by  the  formula 


<•*> 


534  PUMPING,    TOOLS,    AND   MAINTENANCE 

in  which  Q  is  the  quantity  of  water  available  in  cubic  feet  per 
second. 

Of  the  American  makes  of  water-wheels  probably  the  two 
most  extensively  employed  are  the  Victor  turbine  and  the  Leffel 
turbine,  though  a  number  of  other  types  are  manufactured. 
These  wheels  have  been  extensively  employed  for  all  the  various 
purposes  to  which  power  may  be  applied,  and  a  number  of  pump- 
ing plants  for  irrigation  operated  by  such  turbines  have  been 
erected  in  the  West.  These  turbines  come  in  sizes  and  powers 
ranging  from  a  few  inches  in  diameter  under  a  head  of  but  a 
few  feet,  and  capable  of  developing  as  little  as  one  horse-power, 
up  to  the  enormous  sizes  which  have  recently  been  built  for  the 
Niagara  Water  Power  Company,  and  other  similar  concerns, 
which  are  capable  of  developing  as  much  as  5000  horse-power, 
and  which  may  be  operated  under  several  hundred  feet  of  head, 
and  have  diameters  as  great  as  6  or  8  feet.  They  range  in  price 
likewise  from  one  hundred  to  several  thousand  dollars. 

There  has  recently  been  erected  at  Prosser  Falls,  Washing- 
ton, a  turbine  power  and  pumping  plant  capable  of  irrigating 
4000  acres,  besides  furnishing  power  for  factories  and  electric- 
lighting  purposes.  The  water  is  pumped  to  an  elevation  of 
100  feet  with  a  power-producing  fall  of  20  feet,  and  is  deliv- 
ered to  the  turbines  through  a  flume  10  feet  deep  by  12  feet  clear 
width,  and  carrying  6  feet  in  depth  of  water  at  low  stages.  The 
turbines  are  48  inches  diameter,  of  special  Victor  type,  and  there 
are  two  of  these,  each  capable  of  developing  135  horse-power 
under  12  feet  head.  They  operate  a  pair  of  Duplex  pumping- 
engines  of  25-inch  cylinder  and  24-inch  stroke,  each  having 
a  capacity  of  4000  gallons  a  minute.  A  third  pump  is  to  be 
installed,  and  when  erected  the  entire  plant  will  have  a  daily 
capacity  of  about  45  acre-feet. 

397.  Pelton  Water-wheels. — Pelton  water-wheels  are  sim- 
pler in  construction  than  turbine  wheels  and  less  liable  to  be 
clogged  or  to  get  out  of  order,  while  the  ycna  be  worked  under 
much  greater  heights  of  fall  than  can  turbines.  They  are  ver- 
tical, tangential  reaction  wheels,  and  power  is  derived  from  the 
pressure  of  the  head  of  water  supplied  by  a  pipe  which  discharges 


PELTON    WATER-WHEELS  535 

upon  the  wheel -buckets  on  the  lower  side  of  the  wheel  through 
a  small  nozzle,  as  was  the  old  hurdy-gurdy  of  California  mining 
days  operated  by  the  discharge  through  a  hydraulic  monitor. 
Pelton  wheels  are  not  recommended  for  heads  less  than  30  to 
50  feet,  as  below  these  heads  turbines  are  usually  more  efficient, 
though  for  the  production  of  small  powers,  say  10  or  20  horse- 
power, a  Pelton  wheel  will  give  as  great  efficiency  as  any  other 
wheel  with  heads  of  10  to  30  feet.  But  above  50  feet  head  and 
up  to  2000  feet  a  Pelton  wheel  is  best,  as  no  other  wheel  produces 
anything  like  the  same  efficiency  or  works  with  equal  simplicity. 
These  wheels  are  adapted  to  a  wide  range  of  conditions  of  water- 
supply,  producing  power  under  the  most  varying  conditions 
with  almost  equal  efficiency.  This  is  accomplished  by  simple 
change  of  nozzle-tips,  by  varying  the  size  of  stream  thrown  upon 
the  wheel,  the  power  of  which  may  thus  be  varied  from  maximum 
to  25  %  without  appreciable  loss.  The  buckets  being  open,  there 
is  no  uncertainty  or  annoyance  from  derangement  of  the  parts, 
or  stoppage  by  driftwood  or  other  substances  in  the  water.  They 
are  relatively  cheap  of  instalment,  and  may  utilize  the  water 
from  a  small  spring  or  creek  as  well  as  from  the  largest  source 
of  supply.  These  wheels  admit,  by  varying  their  diameter,  of 
being  placed  directly  on  the  crank-shaft  of  power  pumps  without 
intermediate  gearing  or  connections.  The  efficiency  of  Pelton 
wheels  is  perhaps  a  little  higher  than  that  of  turbines,  the  latter 
attaining  efficiencies  of  60%  to  80%,  while  Pelton  wheels  not 
uncommonly  attain  efficiencies  of  70%  to  85%. 

The  buckets  which  are  on  the  periphery  of  a  Pelton  wheel 
—the  latter,  by  the  way,  is  narrow,  not  having  the  broad  diameter 
of  other  vertical  wheels — are  of  metal,  cup-shaped,  and  divided 
into  two  compartments  in  such  way  as  to  develop  the  full  force 
of  the  impinging  stream,  while  in  passing  out  the  water  sweeps 
the  curved  sides  with  a  reactionary  influence,  giving  it  the  effect 
of  a  long  impact.  The  power  of  this  wheel  does  not  depend 
upon  its  diameter,  but  upon  the  volume  and  head  of  water  sup- 
plied. There  are  practically  three  types  of  Pelton  wheel- 
single  nozzle,  double  nozzle,  and  multiple  nozzle — though  there 
are  in  addition  a  number  of  patented  attachments  to  the  wheel, 


536  PUMPING,    TOOLS,    AND    MAINTENANCE 

giving  it  various  names,  as  the  Hett  Pelton  wheel,  the  Caudle 
Pelton  wheel,  and  others,  which  have  no  especial  advantage 
over  the  more  ordinary  forms.  The  single-,  double-,  and  multiple- 
nozzle  wheels,  as  their  names  imply,  may  have  one  or  more 
nozzles  from  which  water  is  directed  tangentially  at  various 
parts  of  the  wheel. 

As  yet  few  Pelton  wheels  have  been  employed  in  pumping 
water  for  irrigation,  but  it  is  not  improbable  that  in  the  near 
future  their  value  in  utilizing  small  volumes  of  water  from  great 
heights  for  this  purpose  will  become  better  appreciated.  Several 
wheels  of  this  character  have  been  erected,  both  for  the  produc- 
tion of  very  small  and  very  large  power.  Some  are  so  small 
as  to  develop  power  from  the  supply  of  a  house  faucet,  running 
little  pumps  for  filling  water-tanks  for  domestic  use.  At  the 
North  Star  mine  in  California  one  of  the  largest  has  recently  been 
constructed  for  pumping,  which  is  operated  under  an  effective 
head  of  750  feet,  the  wheel  being  i8J  feet  in  diameter,  of  300 
H.P.  capacity,  and  mounted  on  a  bicycle-like  spoked  frame  having 
a  lo-inch  steel  shaft  connected  directly  with  air-compressing 
engines  with  a  speed  of  300  feet  a  minute.  The  peripheral 
speed  of  this  wheel  is  6000  feet  a  minute,  and  its  efficiency  is 
believed  to  be  as  high  as  90%.  Another  Pelton  water-wheel 
working  under  810  feet  head,  the  wheel  being  but  40  inches  in 
diameter,  develops  600  horse-power;  and  still  another  wheel 
57  inches  in  diameter  under  1410  feet  head  develops  500  horse- 
power. 

398.  Uses  of  Water-power. — Turbine  and  Pelton  water- 
wheels,  and  in  fact  simple  vertical  water-wheels,  may  be  util- 
ized in  connection  with  irrigating  plants  in  a  reverse  manner 
to  that  just  described;  that  is,  not  for  pumping  water  for  irri- 
gation, but  the  water  which  flows  in  gravity  canals  may  be  util- 
ized to  develop  power  for  various  economic  purposes.  On 
the  lines  of  nearly  all  canals  there  is  wastage  of  power  in  falls 
introduced  at  the  headworks,  at  the  outlets  of  storage  works, 
and  at  various  points  where  falls  are  introduced  to  neutralize 
the  surface  grades.  At  such  points  as  these  turbines  or  Pelton 
wheels  may  be  employed  to  generate  power  which  may  be  util- 


WATER-PRESSURE   ENGINES  537 

ized  for  manufacturing  purposes,  for  electric  lighting  or  trans- 
mission of  power,  or  for  pumping  water  from  low-service  canals 
to  high-service  lines  which  will  bring  under  irrigation  areas 
which  would  otherwise  go  without  water-supply. 

The  water  in  the  Folsom  canal  in  California  is  used  to  de- 
velop power  through  four  pairs  of  turbines,  each  pair  having  a 
capacity  of  1260  horse-power  at  300  revolutions  per  minute, 
operated  under  55  feet  head.  They  develop  5000  horse-power 
for  electric  transmission,  the  remainder  being  employed  for 
power  at  the  site. 

At  Roosevelt  dam  4400  horse-power  are  developed  at  the 
outlet  gates  and  this  may  be  transmitted  electrically  sixty  miles 
to  Mesa  and  Phoenix,  where  it  may  be  utilized  in  pumping  seep- 
age water  from  the  irrigated  lands.  Additional  pumping  plants 
will  be  located  along  the  Verde  River  to  utilize  the  fall  between 
Roosevelt  dam  and  Granite  Reefs  diversion  dam.  On  the  Min- 
nedoka  project,  Idaho,  20,000  to  30,000  horse-power  will  ulti- 
mately be  developed  for  electric  transmission  and  pumping  of  seep- 
age water  to  be  reused  in  irrigation. 

In  Italy  and  India  irrigation  water  is  thus  employed  for  de- 
veloping power;  at  the  Fife  dam  in  Bombay,  and  notably  near 
Cigliano,  Italy,  where  the  water  flowing  in  a  feeder  of  the  Cavour 
canal  is  thus  employed  to  lift  water  to  a  high-level  canal  for 
further  use  in  irrigation.  There  are  diverted  from  the  stream 
three  canals,  between  the  two  lower  of  which  is  placed  an  exten- 
sive turbine  pumping  plant  which  receives  its  water  from  the  upper 
of  these  two  canals  and  tails  into  the  lower  canal,  whence  it  is 
distributed  for  the  irrigation  of  low-lying  fields.  The  third  or 
uppermost  of  these  canals  through  a  wrought-iron  pipe  three 
feet  in  diameter  supplies  water  under  head  of  66  feet  to  the  pumps 
below,  and  these  elevate  it  through  a  pipe  of  the  same  diameter 
to  a  total  height  of  140  feet,  where  it  is  emptied  into  a  fourth 
canal,  which  distributes  it  for  irrigating  the  upper  fields. 

399.  Water-pressure  Engines. — Water-pressure  engines,  as 
their  name  implies,  develop  power  from  the  pressure  of  water 
confined  in  upright  pipes.  They  are  used  to  convert  stored 
into  active  energy,  as  the  water  acts  by  its  weight  alone,  in  oc- 


538  PUMPING,    TOOLS,    AND    MAINTENANCE 

casional  instances  only  being  assisted  by  momentum.  Their 
motion  is  periodical  and  reciprocating,  and  they  are  therefore 
serviceable  when  not  required  to  develop  rotary  motion  as  in 
operating  direct -acting  pumping-engines.  In  using  water-pres- 
sure engines  care  must  be  taken  to  prevent  sudden  checking  of 
the  descending  volume  of  water,  and  to  this  end  escape- valves, 
air-vessels,  accumulators,  or  other  means  of  lessening  shock 
which  the  engine  sustains  are  provided. 

The  principal  parts  of  such  a  machine  are  the  reservoir,  the 
supply-pipe  which  conducts  the  water  from  the  reservoir  to 
the  working  cylinder,  in  which  latter  work  is  performed  by  forc- 
ing upward  a  loaded  driving  piston.  The  cistern  is  relieved 
of  water  after  the  work  is  performed  by  a  discharge-pipe.  A 
regulator  is  placed  in  a  connecting  pipe  which  joins  the  work- 
ing cylinder  with  the  supply-pipe.  These  engines  are  made 
single-  and  double-acting,  and  may  have  one  or  two  cylinders. 
In  the  single-acting  engine  the  piston  is  moved  by  water  pres- 
sure in  one  direction  only,  and  in  the  opposite  direction  by  its 
own  or  added  weight.  In  the  double-acting  engine  the  piston 
is  moved  in  both  directions  by  the  force  of  water.  There  are 
many  designs  and  many  makes  of  these  engines,  and  it  may 
be  said  of  them  that  they  are  better  suited  for  pumping  in  mines 
where  a  great  fall  is  readily  obtainable  and  a  comparatively  small 
volume  is  to  be  elevated  to  a  considerable  height  than  they  are 
for  irrigating  purposes.  There  are  a  few  forms  of  water-pressure 
engines  which  are  rotative,  and  these  are  similar  to  steam-engines 
with  fixed  cylinders,  connecting-rods,  and  fly-wheels,  but  have 
no  flap  on  the  slide-valve.  There  are  also  a  few  designs  of  oscil- 
lating water-pressure  engines,  worked  on  the  principle  of  the 
old  oscillating  marine  engine;  yet  none  of  these  can  be  recom- 
mended especially  for  pumping  water  for  irrigation.  There 
is  not  much  difference  between  rotary  water-pressure  engines 
and  impulse  turbines  other  than  that  the  former  are  less  eco- 
nomical than  the  latter,  which  are  generally  larger  and  more 
efficient. 

No  exhaustive  experiments  have  been  made  to  ascertain 
the  performance  and  economy  of  these  engines.  Where  they 


HYDRAULIC   RAMS  539 

arc  utilized  under  the  most  advantageous  circumstances  their 
efficiency  is  not  infrequently  as  high  as  70%  or  80%.  Water- 
wheels  have  an  advantage  over  water-pressure  engines  in  their 
simplicity  and  cheapness.  Under  small  pressures  water-wheels 
are  preferable.  Under  great  pressures  pressure-engines  may 
att?.in  higher  efficiencies,  but  they  are  much  more  elaborate 
and  expensive  machines  as  compared  with  most  water-wheels, 
except  the  Pelton.  It  may  be  said  that  under  great  pressures, 
where  it  is  desirable  to  make  the  best  use  of  the  water-power 
available,  water-pressure  engines  are  most  economical,  but  where 
water-power  is  abundant,  and  it  is  desired  to  economize  cost, 
turbines  have  the  advantage. 

400.  Hydraulic  Rams. — Where  there  is  a  slight  fall  and  it 
is  desired  to  raise  small  amounts  of  water  the  hydraulic  ram  is 
extremely  simple,  useful,  and  economical.  It  works  on  the 
principle  of  a  large  volume  of  water  having  a  small  fall  forcing 
by  impulse  blows  a  smaller  volume  of  water  to  a  higher  eleva- 
tion. Hydraulic  rams  owe  their  action  to  the  shocks  which  are 
so  objectionable  in  water-pressure  engines.  There  are  three 
classes  of  such  machines:  (i)  those  having  no  air-vessel  in  direct 
communications  with  the  drive-pipe;  (2)  those  having  an  air-vessel 
in  direct  communication  with  the  drive-pipe;  and  (3)  pump- 
ing-rams.  Water  is  delivered  to  the  ram  from  a  reservoir  or  a 
stream  with  steady  flow  through  a  supply-  or  drive-pipe,  at  the 
end  of  which  is  a  check-valve  opening  into  a  chamber  connected 
with  the  discharge-pipe.  In  the  drive-pipe,  near  the  check- 
valve,  is  a  weighted  pulse  or  clack-valve  which  opens  inward, 
the  length  of  stroke  of  which  is  capable  of  regulation.  Sup- 
posing the  water  at  rest  in  the  machine  and  the  deli  very- valve 
closed  and  the  pulse-valve  open,  the  water  that  passes  through 
the  drive-pipe  flows  with  a  velocity  due  to  the  height  of  fall  out 
through  the  pulse-valve,  which  it  almost  immediately  closes. 
At  the  moment  the  issue  of  water  ceases  a  ramming  stroke  is 
created  wrhich  opens  the  deli  very- valve  and  permits  the  water 
to  enter  the  air-vessel,  and  at  the  same  time,  in  consequence 
of  the  shock  to  the  delivery-valve  and  by  virtue  of  its  elasticity, 
the  water  flows  back  through  the  drive-pipe.  At  the  moment 


540  PUMPING,    TOOLS,    AND   MAINTENANCE 

the  backward  motion  begins  the  delivery-valve  closes  and  the 
pulse-valve  opens  to  allow  the  passage  of  water  from  the  drive- 
pipe.  The  alternation  of  these  effects  is  continuous. 

A  general  rule  for  the  discharge  of  hydraulic  rams  is  that 
about  one-seventh  of  the  supply  volume  of  water  can  be  elevated 
to  a  height  five  times  that  of  the  fall,  or  one-fourteenth  part  may 
be  elevated  ten  times  the  height  of  the  fall,  etc.  The  fall  should 
range  from  2  to  10  feet,  but  not  above  this,  owing  to  the  wear 
and  tear  produced  by  the  ramming  stroke.  Among  the  ad- 
vantages of  hydraulic  rams  are  their  small  first  cost  and  very 
small  cost  for  maintenance;  also,  that  they  are  unaffected  by 
tail  water,  and  may  continue  working  even  when  flooded.  They 
are  not  economical  in  water,  as  it  takes  a  large  volume  to  do  a 
small  amount  of  work.  Their  efficiency  is  low,  and  as  the  height 
to  which  the  water  is  elevated  increases  the  efficiency  decreases. 
The  efficiency  of  a  well-designed  ram  working  under  the  most 
advantageous  circumstances  may  be  as  high  as  66%.  With  a 
great  difference  between  the  delivery  and  supply  head  only  a  small 
percentage  of  water  is  pumped.  Let  H  =  height  to  which  water 
is  elevated  and  h  =  head  consumed  in  friction  and  hydraulic  re- 
sistance; then  for  the  actual  work  done 

P  =  w(H-h,),      .....     (13) 

in  which  w  =  weight  of  water  elevated.  The  efficiency  of  a  ram 
may  be  expressed  by  the  formula 


in  which  q  =  quantity  of  working  water  in  gallons,  Q  —  quan- 
tity of  pumped  water  in  gallons,  h  =  head  of  working  fall,  and 
H  =  height  to  which  water  is  pumped.  The  diameter  of  the 
drive-pipe  may  be  gotten  by  the  formula 

d  =  .o$S\/~q  .....     -      -     (15) 

The  length  of  drive-pipe  should  be  increased  with  the  height  to 
which  water  is  to  be  lifted.  A  general  rule  is  to  make  its  length 
equal  five  to  ten  times  the  height  of  fall.  Its  inclination  should 
vary  from  i  in  18  for  small  falls  to  i  in  4  for  high  falls.  The 


HOT-AIR,    GASOLINE,    AND   ALCOHOL   ENGINES          541 

diameter  of  the  delivery-pipe  is  usually  from  J  to  J  the  area  of 
the  drive-pipe.  A  hydraulic  ram  should  be  protected  from  frost 
and  a  strainer  should  be  secured  at  the  upper  end  of  the  drive-pipe. 

But  few  rams  are  sufficiently  powerful  to  pump  water  for 
irrigation.  Most  of  those  which  can  be  used  for  such  purposes 
partake  more  of  the  nature  of  hydraulic-ram  engines  than  of 
hydraulic  rams  proper,  being  so  designed  that  they  may  be 
actuated  by  dirty  water  as  well  as  clear,  and  they  are  more  intri- 
cate in  their  construction  and  valve  arrangement  than  the  simple 
ram.  One  of  the  best  hydraulic  rams  made  for  pumping  large 
volumes  is  the  Rife  hydraulic  engine.  The  largest  of  these  only 
are  capable  of  elevating  enough  water  for  irrigation  purposes. 
Those  having  a  drive-pipe  8  inches  and  a  delivery-pipe  4  inches 
in  diameter  are  capable,  under  a  head  of  10  feet  and  utilizing  one 
second-foot  of  supply  per  minute,  of  elevating  about  J  acre-foot 
per  day  of  24  hours  to  a  height  of  25  feet.  Such  a  machine  costs 
$500,  or  at  the  rate  of  about  $10  per  acre  irrigated  for  first  cost  of 
plant,  and  practically  nothing  for  operation. 

401.  Hot-air,  Gasoline,  and  Alcohol  Pumping-engines.— 
Hot  air  pumping-engines  depend  for  their  operation  on  power 
developed  by  the  expansion  of  heated  air  without  the  interposition 
of  steam  or  other  agency  to  convert  the  heat  into  motion.  Alcohol 
and  gasoline-engines  are  likewise  operated  without  converting 
the  heat  produced  by  combustion  into  steam,  but  depend  upon 
the  expansive  force  produced  by  the  explosion  of  alcohol  or  gaso- 
line converted  into  gas  when  brought  into  contact  with  air.  They 
have  under  certain  conditions  decided  advantages  over  water-  and 
steam-motors  in  that  they  can  be  employed  where  there  is  not  a 
sufficient  water-supply  to  operate  a  water-motor,  utilizing,  as 
they  do,  practically  no  water,  and  therefore  being  able  to  pump 
all  that  is  available  for  irrigation.  They  may  be  employed  where 
steam-pumps  cannot  be,  both  because  of  their  economy  in  water 
consumption  and  because  of  the  kinds  of  fuel  which  they  may 
use;  gasoline  and  alcohol  being  serviceable  in  arid  regions  where 
transportation  of  fuel  is  expensive  and  hot-air  engines  being 
capable  of  utilizing  any  variety  of  fuel.  Again,  they  are  compact, 
and  simple  of  erection  by  comparatively  unskilled  machinists, 


542  PUMPING,    TOOLS,    AND    MAINTENANCE 

and  can  be  operated  at  the  least  expense  for  supervision.  De- 
natured alcohol  is  as  efficient  a  fuel,  pint  for  pint,  as  is  gasoline, 
when  utilized  in  a  specially  designed  alcohol  engine  of  which 
there  are  several  successful  makes  on  the  market.  Such  alcohol 
can  be  made  on  the  farm  from  waste  or  refuse  vegetables,  fruit, 
or  grain. 

Hot-air  engines  are  constructed  almost  wholly  as  pumping- 
engines,  and  the  motive  power  and  pumping  apparatus  are 
combined  in  one  machine  inseparably  connected.  Gasoline-  and 
alcohol-engines  come,  as  do  other  motive  powers,  independent  of 
the  pump,  and  therefore  capable  of  utilization  for  doing  other 
forms  of  work;  but  they  are  also  made  as  direct  connected  pump- 
ing-engines,  both  pump  and  motive  power  being  combined  in  one 
mechanism.  The  only  form  of  hot-air  pumping-engine  on  the 
market  is  the  De  Lamater  hot-air  engine.  Many  thousands  of 
these  machines  are  in  use,  chiefly  for  pumping  small  quantities  of 
water  in  cities  for  manufacturing. or  domestic  uses,  only  a  few 
being  employed  in  pumping  water  for  irrigating.  They  are  so 
simple  of  construction  that  any  one  capable  of  lighting  a  match 
can  operate  them.  There  is  no  possibility  of  explosion,  as  may 
occur  through  carelessness  with  a  gasoline-engine.  When  once 
started  they  require  no  further  attention  than  the  replenishment 
of  fuel.  These  engines  are  made  with  capacities  ranging  from  a 
few  gallons  a  minute  up  to  one  second-foot,  equivalent  to  .  2  of  an 
acre-foot  per  day  of  24  hours,  limited  by  the  height  of  lift,  which 
varies  from  a  few  feet  to  500  feet.  One  of  the  objections  to  hot- 
air  pumping-engines  is  their  great  first  cost,  which  for  the  largest 
sizes — for  example,  those  capable  of  pumping  .2  second-foot — is 
$600,  or,  for  plant  alone,  $3000  per  second-foot,  equivalent  to 
from  $50  to  $75  per  acre  irrigated. 

Gasoline-  and  alcohol-engines  are  used  extensively  in  some 
portions  of  the  West,  notably  in  Kansas,  for  pumping  water  for 
irrigation.  They  are  made  of  various  dimensions  up  to  those 
capable  of  developing  50  H.P.,  and  pumping  a  correspondingly 
large  volume  of  water,  and  they  are  constructed  as  combined 
motive  and  pumping  plants  or  as  separate  motors  to  be  attached 
to  various  forms  of  pumps.  The  chief  advantages  which  these 


PUMPING   BY   STEAM-POWER  543 

machines  have  over  other  motive  powers  for  pumping  are  their 
compactness  and  simplicity  of  installation  and  operation,  but 
above  all  their  cheapness,  not  so  much  for  first  cost  as  for  ultimate 
maintenance,  though  in  this  latter  item  they  do  not  surpass  hot- 
air  pumping  engines.  The  largest  of  these  engines  is  capable 
of  elevating  for  low  heads  as  much  as  10  second-feet  of  water, 
or  20  acre-feet  per  day  of  24  hours,  and  lesser  quantities  to  greater 
heights  in  proportion.  The  cost  of  operation  of  such  a  machine 
as  this  has  been  for  gasoline  as  low  as  2  to  5  cents  per  acre-foot 
and  for  all  expenses  5  to  24  cents,  depending  on  lift.  The  largest 
sizes  will  elevate  sufficient  water  to  a  height  of  50  feet  to  irrigate 
about  320  acres  if  storage  be  provided. 

402.  Pumping  by  Steam-power. — There  are  many  forms  of 
motors  designed  to  utilize  steam-power  in  pumping.  These  may 
be  divided  into  the  following  three  classes: 

1.  Those  in  which  water  is  elevated  directly  by  steam,  as 
injectors  and  pulsometers. 

2.  Those  which  utilize  the  power  developed  by  steam  through 
an  engine  indirectly  by  gearing  and  belting  or  other  separable 
connection. 

3.  Those  which  utilize  steam-power  through  an  engine  di- 
rectly, as  direct-acting  or  fly-wheel  pumping-engines. 

In  considering  steam  as  a  motive  power  it  is  unnecessary  to 
refer  to  any  of  the  forms  of  steam-engines  and  boilers  employed 
in  developing  this  power,  as  their  name  is  legion,  and  they  are 
manufactured  in  all  varieties,  forms,  sizes,  and  prices.  Under 
the  title  of  Pumps  direct-acting  engines  will  have  to  be  considered, 
because  the  motive  power  is  a  portion  of  the  pumping  mechanism. 
Such  is  also  the  case  with  pulsometers,  vacuum-pumps,  and  in- 
jectors. 

The  only  feature  of  steam  as  a  motive  power  which  it  is  de- 
sirable to  consider  is  the  cost  and  economy  of  producing  power 
for  pumping  purposes  and  the  amount  of  work  which  a  given 
power  will  perform.  This  consideration  of  power  in  elevating 
water  is  one  which  bears  the  same  relation  to  its  other  forms  as 
does  the  power  produced  by  water  or  by  air,  and  therefore  the 
facts  here  developed  have  immediate  bearing  on  the  powers 


544  PUMPING,    TOOLS,    AND    MAINTENANCE 

produced  by  water-motors  as  well  as  steam-motors.  According 
to  Mr.  J.  T.  Fanning,  the  power  P  in  foot-pounds  required  to 
produce  a  given  flow  of  water  by  pumping  is 

P  =  QWh,       ......      (16) 

in  which  Q  =  volume  in  cubic  feet  of  water  to  be  set  in  motion, 
W  =  the  weight  of  a  cubic  foot  of  water  in  pounds,  equal  to  62.5 

Ibs.,  and  h  =  —  is  the  height  in  feet  to  which  the  rate  of  motion 

2g 

is  due. 

The  power  required  to  accelerate  the  motion  of  water  is  in 
addition  to  the  dynamic  power,  p,  in  foot-pounds  required  to 
lift  it  through  a  height,  H,  of  actual  elevation,  and  the  equation 
of  lifting  per  second,  disregarding  frictional  resistance,  is 

P-QWH,      ......     (17) 

or  for  any  time 

p  =  tQWH.     ......     (18) 

The  frictional  resistance,  F,  to  flow  in  a  straight  pipe  is  pro- 
portional about  to  the  square  of  the  velocity  of  flow,  and  is  com- 
puted by  some  formula  for  friction  head,  hv  among  which,  for 
lengths  exceeding  1000  feet,  is 

4/JfV 


in  which  /  is  the  length  of  pipe  in  feet,  while  the  coefficient  F 
may  be  derived  from  the  tables  of  resistance  to  flow  in  pipes 
given  in  Chapter  XIV. 

The  equation  of  power  pv  required  to  overcome  the  fric- 
tional resistance  to  flow  in  pipes,  in  which  hl  is  the  vertical  height 
of  lift  in  feet  equivalent  to  frictional  resistance,  is 

(20) 
As  one  horse-power  =  33,000  foot-pounds  per  minute, 

P9 

....        (21) 


33,000 
in  which  P  is  the  power  in  foot-pounds  required  to  produce  a 


PRODUCER   GAS    POWER  545 

given  flow  and  5  is  the  number  of  strokes  of  the  pump  per 
minute. 

The  horse-power  required   to  overcome   the  combined  dy- 
namic lift  and  frictional  resistance  to  flow  for  a  given  time,  /,  is 

(22) 


33,000 

403.  Producer  Gas  Power.  —  Gas  generated  in  a  producer  and 
utilized  in   an  internal   combustion  engine  furnishes  the   most 
efficient  and  economic  power  under  certain  conditions.     Coal 
converted  into  power  under  a  steam  boiler  will  develop  5  to  8 
per  cent  of  the  latent  energy  of  the  fuel  while  in  a  producer  gas 
plant  it  will  develop  2\  times  as  much  power  or  12  to  20  per  cent 
of  the  latent  energy. 

In  many  parts  of  the  arid  West,  where  good  steaming-coal  is 
scarce  and  expensive,  there  are  unlimited  supplies  of  cheap 
lignite,  worth  one  to  two  dollars  per  ton  near  the  mine.  This  is 
not  a  good  steaming-fuel  but  in  the  gas  producer  it  develops  as 
high  efficiency,  often  one  pound  of  lignite  per  B.H.P.,  as  does  the 
best  eastern  coal  under  a  steam  boiler. 

Gas  producers  are  of  two  types,  (a)  suction  and  (b)  pressure. 
The  former  are  at  present  made  only  in  small  powers,  for  25  to 
100  H.P.,  and  are  not  as  yet  well  adapted  to  the  use  of  fuels  so 
high  in  volatile  matter  as  lignite.  Pressure  producers  are  made 
in  sizes  from  100  to  500  H.P.,  and  may  be  used  in  batteries  de- 
veloping several  thousand  horse-power.  They  may  be  success- 
fully operated  on  lignite,  peat,  or  wood,  as  well  as  on  all  varieties 
of  coal. 

The  gas  generated  is  exploded  in  a  gas  engine  which  may  be 
of  any  of  the  regular  makes,  directly  or  indirectly  connected  with 
a  pump.  Or  the  producer  gas  plant  may  be  located  at  a  distance 
from  the  pump,  as  at  a  mine,  and  the  power  generated  be  con- 
verted into  electricity  and  transported  to  the  pumping  station,  as 
is  done  with  the  steam  power  plant  of  the  Reclamation  Service 
at  the  Williston-Trenton-Buford  project  (Art.  408). 

404.  Energy,    Work,    and    Power.  —  In    considering    energy 
expended  in  lifting  water  and  useful  work  accomplished,  the 
following  equivalents  are  helpful. 

35 


546  PUMPING,    TOOLS,    AND    MAINTENANCE 

TABLE  XXX. 

EQUIVALENT    UNITS    OF    ENERGY. 

i  cu.  ft.  water  at  39  .  2°  Fahr.  =  7  .48055  U.S.  gals.=  .028316  cu.  meter=62.396i  Ibs. 

0.13368  =i  '     =.003785  "        "     =    8.34112  " 

35.31563       "  '       =264.179    "        "     =        i         "        "     =    2203.55  " 

0.016027    "  =0.119888"        "     =.000454  "        "     =        i          lb. 

Any  form  of  energy,  as  wind  or  water  pressure,  steam  or 
electric  power,  may  be  utilized  in  lifting  water  through  the  medium 
of  various  pumping  devices.  The  following  are  some  of  the 
more  useful  equivalent  units  of  work. 

TABLE  XXXI. 

EQUIVALENT    UNITS    OF   WORK.       i 

i  horse-power-hour  =  1,980,000  foot-pounds. 

i  kilowatt-hour=2,654,i5o  foot-pounds. 

i  pound  of  steam  =7  78,000  foot-pounds. 

i  pound  of  hard  coal  =  11,400,000  foot-pounds. 

i  pound  of  soft  coal =9,9 1 0,000  foot-pounds. 

100  cu.  ft.  i  ft.  high  (water)  =  62, 396  foot-pounds. 

In  considering  the  equivalents  of  various  heads  of  water, 
it  is  well  to  know  that  i  foot  of  head  =  0.4335  pound  per  square 
inch  =  62.396  pounds  per  square  foot  =  0.02945  atmosphere.  Also 
thpt  i  pound  pressure  per  square  inch  =  0.01602  foot-head. 

Among  the  more  useful  units  of  power  are  the  following  with 
their  equivalents. 

405.  Centrifugal  and  Rotary  Pumps. — For  lifting  large 
volumes  of  water  to  moderate  heights  the  centrifugal  pump 
excels  in  economy,  efficiency,  and  simplicity  of  construction,  and 
in  cost  both  for  plant  and  its  maintenance.  Where  circum- 
stances are  suited  to  its  employment,  it  is  perhaps  the  best  pump 
for  irrigation.  Being  valveless,  it  is  well  adapted  to  raising 
water  containing  sediment  or  foreign  matter.  It  is  continuous 
in  its  action,  and  is  easily  erected  and  operated  by  machinists 
of  moderate  skill. 

A  centrifugal  pump  is  essentially  an  outward-flow  turbine 
driven  in  the  reverse  direction.  Water  enters  the  pump  with- 
out any  velocity  of  whirl,  and  leaves  it  with  a  whirling  velocity 


CENTRIFUGAL  AND  ROTARY  PUMPS 


547 


TABLE  XXXII. 

EQUIVALENT    UNITS   OF    POWER. 

i  horse-power  =33,000  foot-pounds  per  minute  =  42,4i6  thermal  units  per  minute 

=  0.0226  watt=  .0069  pound  cu.  ft.  per  minute. 
.00134  horse-power=  44.24  foot-pounds  per  minute=.o568  thermal  unit=i  watt 

=  .307  pound  cu.  ft.  per  minute. 
.02357  horse-power  =7 78  foot-pounds  per  minute  =  i  thermal  unit=i7-58  watts 

=  5.388  pounds  cu.  ft.  per  minute. 
.00436  horse-power=  144.92  foot-pounds  per  minute=.i857  thermal  unit=.o326 

watt=  i  pound  cu.  ft.  per  minute. 


One  Watt. 


One  Kilowatt. 


One  Horse-power 


One  Watt-Hour. 


One  Horse-power-Hour 

One  Ampere-Hour.  . . . 
Torque  


A  RATE  of  doing  work. 

i .  ampere  per  second  at  i 

•7373    foot-pound  per  second. 
44.238      foot-pounds  per  minute. 
2654.28         foot-pounds  per  hour. 
.5027     mile-pound  per  hour. 
.00134  horse-power. 
Tf^g  horse-power. 


volt. 


A  RATE  of  doing  work. 

737.3     foot-pounds  per  second. 
44238.       foot-pounds  per  minute. 

502.7    mile-pounds  per  hour. 
1.34  horse-power. 

f  A  RATE  of  doing  work. 

550.         foot-pounds  per  second. 
33000.         foot-pounds  per  minute. 
375.         mile-pounds  per  hour. 
764.         watts. 

.746  kilowatt. 
A  QUANTITY  of  work. 
2654.28         foot-pounds. 
.  503       mile-pound, 
i.  ampere  hourXi  volt 

.00134  horse-power-hour. 
rtx    horse-power-hour. 

A  QUANTITY  of  work. 
1,980,000.         foot-pounds. 

375.         mile-pounds. 

746.         watt-hours. 
.746  kilowatt-hour. 

A  QUANTITY  of  current. 

One   ampere  flowing  for   i   hour,  irrespective  of  the 

voltage. 
Watt-hour -i-  volts. 

FORCE  moving  in  a  circle. 

A  force  of  i  pound  at  a  radius  of  i  foot. 


548  PUMPING,    TOOLS,    AND    MAINTENANCE 

which  must  be  reduced  to  a  minimum  in  the  action  of  lifting. 
The  direction  of  the  water  as  it  flows  toward  the  discharge-pipe 
is  controlled  by  a  single  guide-blade,  which  is  the  volute  or  outer 
surface  of  the  pump-chamber  into  which  water  flows  on  leaving 
the  fan.  A  centrifugal  pump  cannot  be  put  into  action  until 
it  has  been  filled  with  water,  which  operation  is  effected  through 
an  opening  in  the  casing  when  the  pump  is  below  water  or  when 
above  water  by  creating  a  vacuum  in  the  pump-chamber  by  means 
of  an  air  or  steam  jet  which  raises  the  water  into  the  suction-tube. 
In  action  the  water  rotates  in  the  pump  as  a  solid  mass,  and 
delivery  only  commences  when  the  speed  is  such  that  the  head 
due  to  centrifugal  force  exceeds  the  lift,  though  this  speed  may 
afterwards  be  reduced.  As  the  pump  commences  to  operate 
the  water  rises  in  the  suction-tube  and  divides  so  as  to  enter 
the  center  of  the  pump-disk  on  both  sides.  The  revolving  pump- 
disk  or  fan,  as  in  a  turbine,  is  provided  with  vanes  or  blades 
curved  so  as  to  receive  the  water  at  the  inlet  surface  without 
shock — an  effect  obtained  by  so  proportioning  the  pump  as  to 
give  a  gradually  increasing  velocity  to  the  water  until  it  reaches 
the  outer  ends  of  the  vanes  and  then  a  gradually  decreasing 
velocity  until  it  reaches  the  discharge-pipe,  a  result  obtained 
in  construction  by  conical  ends  to  both  suction-  and  delivery- 
pipes  and  a  spiral  casing.  The  water  leaves  the  surfaces  of  the 
vanes  with  more  or  less  velocity  and  impinges  upon  the  mass  of 
water  flowing  around  inside  the  outer  casing  towards  the  dis- 
charge-pipe, and  this  casing  must  have  a  section  gradually  in- 
creasing to  the  point  of  discharge  in  order  that  delivery  across 
any  section  of  it  may  be  uniform.  This  section  is  also  designed 
so  as  to  compel  rotation  in  one  direction  only  with  a  velocity 
corresponding  to  the  velocity  of  the  whirl  on  leaving  the  pump- 
disk. 

Nearly  all  centrifugal  pumps  are  provided  with  a  vortex-  or 
whirlpool-chamber  in  which  the  water  discharged  from  the  re- 
volving vanes  continues  to  rotate,  and  here  the  kinetic  energy 
is  converted  into  pressure  energy  which  would  otherwise  be 
wasted  in  eddies  in  the  confining  chamber.  This  vortex-chamber 
is  provided  with  guide-blades  following  the  direction  of  the 


CENTRIFUGAL   AND    ROTARY    PUMPS  549 

stream  lines  so  as  to  prevent  irregular  motion.  The  working 
parts  of  a  centrifugal  pump  accordingly  consist  of  a  series  of 
curved  disks  or  vanes  mounted  on  a  spindle  and  revolving  in  a 
chamber  in  a  manner  similar  to  a  fan-blower.  A  revolution 
of  each  vane  within  this  closed  case  produces  a  partial  vacuum 
which  draws  up  the  water,  and  it  is  on  a  proper  proportioning 
and  arrangement  of  these  vanes  that  the  effective  working  of 
the  pump  chiefly  depends.  These  pumps  are  so  constructed 
that  the  casing  may  be  removed  to  allow  of  the  inspection  and 
cleaning  of  the  pump-disks.  The  curved  vanes  are  made  of  the 
best  steel  or  phosphor-bronze  and  the  pump-disks  should  be 
perfectly  balanced  in  order  to  produce  even  motion  in  the  water. 

The  efficiency  of  a  simple  centrifugal  pump  diminishes  with 
the  lift,  and  for  lifts  exceeding  25  to  30  feet  a  plunger-pump  pro- 
duces better  results.  Centrifugal  pumps  are  driven  by  belting 
or  shafting  or  they  may  be  directly  connected  to  the  motor-shaft. 
The  more  rapidly  the  pump-disk  rotates,  the  lift  remaining 
constant,  the  smaller  is  the  centrifugal  force — a  peculiar  con- 
dition, due  to  the  fact  that  as  the  discharge  increases  the  velocity 
of  the  water  in  the  casing  more  nearly  approaches  that  of  the 
water  leaving  the  pump-disk,  and  therefore  the  efficiency  of 
the  pump  improves,  and  with  it  the  theoretical  lift  diminishes 
as  well  as  the  centrifugal  force.  Another  peculiar  property  of 
centrifugal  pumps  is  that  a  small  increase  in  the  number  of  revo- 
lutions after  it  has  begun  discharging  produces  a  very  large  in- 
crease in  the  delivery.  The  highest  efficiency  ordinarily  obtained 
by  simple  centrifugal  pumps  is  from  65  to  70  per  cent,  and  ex- 
periments seem  to  indicate  that  the  efficiency  of  a  centrifugal 
pump  increases  as  its  size  increases.  Thp'.s,  a  pump  with  2-inch 
discharge-pipe  will  give  an  efficiency  of  38  per  cent,  while  a  3-inch 
pipe  will  give  a  45  per  cent  efficiency  and  a  6-inch  pump  a  65  per 
cent  efficiency.  From  this  it  appears  that  a  centrifugal  pump  is 
to  be  recommended  rather  where  large  volumes  of  water  are  to  be 
lifted. 

Rotary  pumps  are  theoretically  among  the  most  efficient, 
and  their  form  is  a  favorite  among  experimenters  in  pump  designs. 
They  are,  however,  capable  of  elevating  but  small  quantities  of 


550  PUMPING,    TOOLS,    AND   MAINTENANCE 

water,  and  are  of  little  value  for  elevating  water  for  irrigation. 
They  may  be  termed  revolving  piston-pumps  in  distinction  from 
direct-acting  pumps,  and  have  the  advantage  of  not  changing  the 
direction  of  flow  of  the  water  during  its  elevation  by  each  stroke 
of  the  pump.  They  can  be  run  at  a  high  speed,  and  have  no 
complicated  leather  valves  or  pistons  to  be  choked  or  get  out  of 
order.  These  pumps  may  be  divided  into  two  classes,  according 
to  the  forms  and  methods  of  working  the  revolving  pistons  and 
the  manner  in  which  the  butment  is  obtained.  The  efficiency 
of  rotary  pumps  is  low,  there  being  a  great  excess  in  driving  power 
required  over  useful  work  performed,  caused  chiefly  by  the  inertia 
of  water  or  difficulty  of  putting  it  in  motion  after  it  has  been 
brought  to  rest  and  the  necessity  of  imparting  at  certain  moments 
a  high  velocity  to  a  large  volume  of  water,  which  calls  for  the 
expenditure  of  considerable  power. 

406.  Examples  of  Centrifugal  Pumping  Plants. — Centrifugal 
pumps  are  made  both  to  be  worked  separately  by  transmitted 
power  or  by  motors  directly  connected  to  the  pump  frame,  and 
are  of  varying  capacities,  from  those  having  2-inch  discharge- 
pipes  up  to  those  having  45-inch  discharge-pipes,  the  largest 
sizes  being  capable  of  elevating  as  much  as  100  second-feet,  or 
the  same  number  of  acre-feet,  in  a  day  of  1 2  hours.  Centrifugal 
pumps  may  be  either  single  or  compound,  the  latter  being  also 
called  turbine  pumps.  Single  stage  pumps  are  generally  used 
for  low  lifts  while  multiple  stage  pumps,  made  in  4  to  8  stages, 
will  lift  water  from  100  to  1000  feet.  These  pumps  come  in 
very  large  sizes,  capable  even  of  lifting  5,000,000  to  10,000,000 
second-feet  in  24  hours.  When  made  direct-connected  to  steam 
turbines  or  producer  gas-engines,  they  are  of  high  efficiency. 
Such  pumps  cost  for  plant  from  $10  to  $30  per  acre-foot  lifted 
to  moderate  heights  and  from  $5  to  $10  per  acre-foot  per  annum 
for  operation. 

A  centrifugal  pumping  plant  for  irrigation  for  the  Vermilion 
Canal  Company  in  Louisiana  consists  of  six  1 5-inch  pumps, 
capable  of  discharging  130  second-feet  of  water  against  a  head  of 
20  feet,  and  are  operated  by  two  engines,  each  of  250  H.P.  A 
centrifugal  pump  in  southern  Arizona,  operated  by  a  lo-H.P. 


PUMPING-ENGINES  551 

engine  and  boiler,  has  a  capacity  of  two-thirds  of  a  second-foot 
a  day.  The  operation  of  this  plant  calls  for  the  consumption 
of  about  one  cord  of  wood  per  24  hours,  and  it  is  capable  of 
irrigating  about  three  acres  in  a  season.  A  similar  pump  in  the 
same  locality  and  operated  by  a  gasoline  engine  of  35  H.P.  will 
handle  about  nj  acre-feet  in  24  hours,  on  a  consumption  of 
about  84  gallons  of  gasoline.  Other  centrifugal  pumps  of  small 
capacities  and  capable  of  watering  5  to  10  acres  per  day,  and  in 
the  course  of  an  irrigation  season  from  50  to  100  acres,  are 
operated  by  one  man  at  a  cost  of  about  $2.50  per  acre  irrigated 
for  maintenance  and  $15  per  acre  for  first  cost  of  plant.  A 
centrifugal  pump  at  Yuma,  Ariz.,  lifts  3  acre-feet  of  water  per 
hour  a  height  of  10  feet  at  a  cost  of  $0.54  per  acre-foot. 

407.  Pumping-engines. — These  may  be  either  direct-acting, 
or  pump  and  motor  may  be  indirectly  connected  by  belting  or 
shafting.  In  general  it  may  be  stated  that  fly-wheel  pumping- 
engines  which  give  high  duty  under  the  conditions  of  municipal 
water  service,  and  other  forms  of  indirect  pumping-engines,  are 
not  the  most  efficient  and  economical  for  purposes  of  irrigation. 
Direct-acting  pumping-engines  have  a  reciprocating  motion,  and 
may  be  either  single-  or  double-acting.  They  may  be  either 
steam  pumping-engines  or  the  water  end  of  a  direct-acting  pump 
may  be  operated  through  gearing  from  water-,  electric-,  gas-, 
gasoline-,  or  alcohol-motors. 

Direct-acting  steam-pumps  have  the  water  and  steam  ends 
centered  in  line  one  with  the  other  so  that  the  water-plunger  and 
motor-piston  are  attached  to  the  same  piston-rod  and  work 
together  without  an  intervening  crank  or  other  connection.  This 
is  the  simplest  and  most  compact  form  of  pumping-engine,  and 
is  more  extensively  used  for  pumping  than  all  other  varieties  of 
pumping  machinery  combined,  though  it  is  perhaps  one  of  the 
most  wasteful  and  expensive  forms  of  steam-engines. 

In  selecting  steam  pumping-engines,  among  the  points  most 
desirable  are  strength  and  simplicity  of  working  parts;  large 
water-valve  area;  long  stroke  and  ample  wearing  surfaces; 
continuity  of  steam  flow;  simplicity  of  adjustment  and  repair; 
moderate  steam  consumption.  In  choosing  from  the  various 


552  PUMPING,    TOOLS,    AND   MAINTENANCE 

makes  of  pumping-engines  It  is  well  in  corresponding  with  the 
makers  to  inform  them  among  other  points  of  the  purposes  for 
which  they  are  to  be  used;  height  of  lift  and  height  to  which 
water  is  to  be  forced;  quantity  of  water  to  be  elevated;  motive 
power;  and  quality  of  water  as  clear  or  muddy. 

Direct-acting  steam  pumping-engines  may  be  either  high- 
pressure  or  compound.  In  the  latter  case  they  are  economical 
in  both  fuel  and  water  consumption,  and  their  cost  for  opera- 
tion is  therefore  correspondingly  less,  though  their  first  cost  is 
a  little  greater.  The  best  form  of  direct-acting  pumping-engines 
are  Duplex  pumping-engines,  consisting  of  two  direct-acting 
steam  pumping-engines  of  equal  dimensions,  side  by  side  on 
the  same  bed-plate,  with  a  valve  motion  so  designed  that  the 
movement  of  the  steam-piston  of  one  pump  shall  control  the 
movement  of  the  slide-valve  of  its  opposite  pump  so  as  to  allow 
one  piston  to  proceed  to  the  end  of  the  stroke  and  come  to  rest 
while  the  other  piston  moves  forward  on  its  stroke. 

Direct-acting  pumping-engines  are  made  to  operate  also  with 
gas,  gasoline,  alcohol,  electricity,  or  water  as  the  motive  power, 
and  in  great  variety  of  design  and  capacity. 

All  single-acting  pumps  should  be  provided  with  air-cham- 
bers, while  these  are  a  decided  addition  even  to  double-acting 
pumps,  for  though  the  latter  have  a  fairly  steady  discharge, 
the  air-chamber  insures  almost  perfect  uniformity  of  delivery. 
The  capacity  of  an  air-chamber  for  a  pair  of  double-acting  pumps 
is  about  five  or  six  times  the  combined  capacities  of  the  water- 
cylinders,  while  for  a  single-acting  pump  it  may  be  ten  or  twenty 
times  greater.  The  air-chamber  performs  practically  the  office 
of  a  stand-pipe  attached  directly  to  the  pump.  It  neutralizes 
the  variations  of  velocity  of  discharge  in  the  delivery-pipes, 
the  fluctuations  of  which  might  cause  danger  of  ramming  and 
wastage  of  work.  The  air-chamber  obviates  this  by  permitting 
the  excessive  delivery  of  water  from  a  pump-stroke  to  enter  it 
and  thus  compress  the  air,  while  on  the  return  stroke  the  ex- 
pansion of  the  air  forces  out  water  to  supply  the  deficiency. 

408.  Examples  of  Steam  Pumping  Plants. — Several  exten- 
sive steam  pumping  plants  have  been  introduced  in  the-*  West 


EXAMPLES    OF    STEAM   PUMPING   PLANTS  553 

for  providing  water  for  irrigation.  Their  first  cost  is  usually 
less  than  for  gas  or  hydro-electric  plants,  though  not  always  so, 
depending  upon  the  power  generated.  Their  efficiency,  in  large 
units,  is  usually  quite  high  as  compared  with  all  other  forms  of 
pumping  plants,  and  their  maintenance  cost  is  usually  a  little 
less,  excepting  hydro-electric  plants. 

In  Arizona  is  a  high-pressure  steam  pumping-engine  capable 
of  irrigating  100  acres  per  season  which  cost  when  erected  $ioco, 
or  $10  per  acre  irrigated,  while  the  cost  of  runndng  it  is  but  $5  per 
acre.  A  larger  and  more  modern  plant  operated  near  Tucson 
consists  of  two  compound  steam  pumping-engines,  capable  of 
irrigating  600  acres  per  season  at  a  cost  for  operation  of  $3  per 
day,  the  first  cost  for  this  plant  laid  down  having  been  $4200, 
or  $7  per  acre,  and  the  height  of  lift  being  70  feet.  Still  another 
consists  of  an  automatic  cut-off  condensingrengine  with  two  150- 
horse-power  boilers.  The  pumping-engine  which  has  1 8-inch 
stroke  and  42-inch  cylinders,  and  is  of  165  H.P.  capacity,  has  a 
fly-wheel  weighing  7  tons  and  making  67  revolutions  per  minute, 
the  capacity  of  the  pump  being  12  second-feet,  or  about  24  acre- 
feet  in  a  day  of  24  hours.  This  pump  delivers  water  through  a 
26-inch  redwood  stave  main,  elevating  the  water  80  feet,  and 
this  is  stored  in  a  reservoir  having  23  acre-feet  capacity.  A  year's 
test  of  this  engine  shows  it  to  be  capable  of  discharging  12  second- 
feet  at  a  cost  of  $3  per  second-foot  for  fuel. 

A  pumping  plant  designed  by  the  writer  and  employed  for 
the  irrigation  of  1000  acres  consists  of  a  duplicate  set  of  duplex 
compound  pumping-engines  each  capable  of  elevating  25  sec- 
ond-feet with  a  suction  height  of  15  feet  and  forced  to  an  ele- 
vation of  40  feet.  Such  a  plant  in  Arizona  cost  $10  per  acre 
controlled,  and  for  operation  not  exceeding  $0.75  per  acre. 

In  the  Gila  valley,  Arizona,  one  steam-pump,  with  wood 
for  fuel,  raises  water  44  feet  at  a  cost  of  $2.27  per  acre-foot  and 
another  raises  it  50  feet  for  $2.50  per  acre-foot.  Others  give 
costs  for  small  engines  up  to  50  horse-power,  ranging  between 
$2  and  $4  per  acre-foot  for  similar  lifts.  The  cost  per  hour 
for  operation  is  $1.26  and  per  horse-power  per  year  $137.97. 

The  Reclamation  Service  has  erected   at  Williston,  N.  D. 


554 


PUMPING,    TOOLS,    AND    MAINTENANCE 


near  a  lignite  mine,  a  steam-power  electric  generating  plant 
whence  the  electricity  developed  is  transmitted  long  distances  for 
pumping  water  from  the  Missouri  River  for  irrigation  on  the 
Williston  and  the  Buford-Trenton  projects.  There  are  8 
electrically  operated  pumping  stations  requiring  about  1500 
kilowatts  from  the  Williston  power-station. 


HALF  LONGITUDINAL  ELEVATION 

SHOWING  SIDE  TRUSSES 


HALF  LONGITUDINAL    SECTION 

SHOWING  DOUBLE  CENTER  TRUSS 


FIG.  193. — Floating  Pumping  Station,  Buford-Trenton  Project,  N.  D. 

The  pumping  installations  and  canals  are  designed  for  de- 
livering i  cubic  foot  for  80  acres  or  2  acre-feet  per  acre  in  an  eighty 
days  irrigation  season.  The  main  Buford-Trenton  intake 
pumping-station  consists  of  four  electrically  operated  centrifugal 
pumps  on  a  scow  which  rises  and  falls  with  the  fluctuations  of 
the  river  (Fig.  193).  The  pumps  have  a  combined  capacity  of 
150  second-feet  with  a  lift  of  28  feet  and  discharge  into  a  settling 


COST   OF    VARIOUS    POWERS    AND   OF    PUMPING 


555 


basin.  A  second  set  of  similar  pumps,  in  a  concrete  building 
600  feet  from  the  river,  pump  the  water  from  the  settling  basin 
through  one-half  mile  of  reinforced  concrete  pipe  to  a  canal 
which  commands  6,000  acres.  The  total  lift  here  is  85  feet  and 
the  pumping  capacity  75  second-feet. 

There  is  a  similar  main  intake  station  at  Williston  and  other 
stations  lifting  to  high  line  canals.  The  transmission  is  at  22,000 
volts  over  about  25  miles  for  each  project. 

409.  Cost  of  Various  Powers  and  of  Pumping. — The  capital 
and  annual  cost  of  steam,  producer  gas,  and  hydro-electric  power 
per  brake  horse-power  is  given  in  the  following  table: 


Capital  Cost  of  Plant  per  B.  H.  P. 

Annual  Cost  of  24  Hour-Power  per 
B.H.P. 

Rated  Horse 

Power 

Steam. 

Producer 
Gas. 

Hydro- 
electric. 

Steam. 

Producer 
Gas. 

Hydro- 
electric. 

10 

$100 

Si  75 

$150 

$90 

5° 

75 

I05 

IOO 

55 

100 

70 

TOO 

$125 

80 

45 

$40 

500 

60 

80 

IOO 

5° 

40 

30 

IOOO 

55 

70 

80 

40 

35 

25 

An  increase  of  50  cents  per  ton  in  the  price  of  coal  means  an 
additional  cost  per  B.H.P.  for  24  hour-power  ranging  from  $3 
for  large  installations  to  $15  for  small  ones. 

The  cost  of  producing  electric  energy  for  an  installation  of 
about  1000  horse-power,  from  different  sources  of  power,  per 
kilowatt  year,  and  including  interest  and  depreciation  on  capital 
cost,  annual  running  expenses,  etc.,  varies  as  follows: 

For  steam,  $55;  producer  gas,  $60;  oil,  $86;  and  hydro- 
electricity,  $37. 

The  results  of  an  extensive  series  of  tests  of  pumping-plants 
made  in  California  by  the  United  States  Department  of  Agri- 
culture furnish  some  exact  data  on  the  cost  of  pumping  water 
for  irrigation  by  steam,  gasoline,  and  electric  power.  The  cost 
of  lifting  one  acre-foot  of  water  one  foot  high  ranged  for  gasoline 
from  4  to  25  cents;  for  steam  from  2  to  13  cents;  and  for  electricity 
from  8  to  21  cents;  this  with  gasoline  at  6  cents  per  gallon  and 
with  crude  oil  fuel  for  generating  steam  at  less  than  $i  per  barrel 


556  PUMPING,    TOOLS,    AND   MAINTENANCE 

The  cost  of  electricity  was  2  cents  per  kw.  hour.  The  gasoline 
plants  ranged  from  14  to  63  horse-power;  steam  plants  from  30 
to  239  horse-power,  and  the  electrically  driven  from  5  to  39  horse- 
power. The  lifts  varied  from  22  to  247  feet,  and  within  these 
limits  it  cost  the  irrigators  to  pump  one  acre-foot  of  water  from 
$i  to  $46  with  gasoline,  from  $0.54  to  $9.60  with  steam,  and  from 
$1.96  to  $19.20  with  electricity. 

410.  Pulsometers  and  Mechanical  Elevators. — Pulsometers 
are  mechanisms  for  lifting  water  by  the  direct  action  of  steam. 
They  are  most  advantageously  employed  for  rough  work  and  in 
difficult  situations,  chiefly  because  of  their  portability,  as  they 
can  be  readily  moved  from  one  point  to  another.  The  pulsom- 
eter  is  capable  of  utilizing  very  dirty  water,  but  its  capacity  is 
so  limited  as  to  render  it  practically  of  small  value  in  pumping 
water  for  irrigation.  It  consists  of  a  couple  of  pear-shaped 
vessels  in  one  casting,  the  necks  of  which  terminate  in  a  single 
chamber.  It  is  designed  somewhat  on  the  plan  of  the  human 
heart,  wherein  two  valve-seats  are  arranged  with  one  ball-valve 
which  oscillates  between  them.  It  also  has  an  air-chamber, 
suction-  and  delivery-valves.  When  charged  with  water,  steam 
is  admitted  and  presses  on  the  water  surface  in  one  chamber, 
forcing  it  through  the  delivery-valve  into  the  delivery-pipe. 
When  the  steam  reaches  the  opening  leading  to  the  discharge- 
pipe  it  comes  in  contact  with  the  water  already  in  the  pipe,  and 
is  immediately  condensed,  forming  a  vacuum  in  the  chambei 
just  emptied.  This  vacuum  draws  the  ball-valve  over  to  the 
seat  opposite  that  which  it  previously  occupied,  and  prevents  for 
the  time  further  admission  of  steam,  and  to  fill  the  vacuum  thus 
formed  water  rises  through  the  suction-pipe  and  fills  the  empty 
chamber,  an  operation  which  is  repeated  indefinitely.  Pulsom- 
eters contain  practically  no  movable  parts;  wear  is  reduced  to 
a  minimum,  very  little  attention  is  required  in  their  use,  and  there 
is  little  chance  of  clogging  the  valves  by  dirty  material,  but  their 
efficiency  is  extremely  low. 

A  modern  mechanical  water-elevator,  somewhat  like  the  old 
chain-and-bucket  pump,  consists  of  an  elongated  box  which  can 
be  set  up  over  the  well  or  other  water-supply.  At  either  end  of 


IRRIGATION    TOOLS  557 

this  box  is  a  wheel  carrying  on  its  periphery  a  metal  link  belt  or 
chain,  having  attached  to  it  at  short  intervals  wooden  projections 
of  such  dimensions  as  completely  to  fill  the  cross-section  of  the 
box.  These  projections,  or  flights  as  they  are  called,  close  the 
space  in  the  box  between  each  flight,  and  as  the  chain  revolves 
they  are  raised,  carrying  with  them  the  water  resting  upon  them 
and  preventing  it  from  running  back.  This  machine  may  be 
operated  by  animal,  wind,  steam,  or  water  power,  as  desired. 
The  largest  size  made  is  capable  of  lifting  about  5  second-feet 
or  5  acre-feet  in  a  working  day  of  12  hours,  with  an  expendi- 
ture of  7  horse-power  for  a  lo-foot  lift.  The  highest  satisfactory 
lift  of  these  machines  is  about  20  feet,  and  the  cost  of  a  machine 
of  this  capacity  is  about  $50  per  second-foot,  or  $i  per  acre  con- 
trolled, a  comparatively  trivial  outlay  for  first  cost  of  pumping 
plant,  excepting  the  motive  power. 

411.  Irrigation  Tools. — There  is  little   to  say  of  the   tools 
required  in  the  construction  and  management  of  irrigation  works. 
Agricultural-tool  makers  now  manufacture  hoes,  spades,  shovel?, 
and  ploughs  of  special  designs  for  the  making  and  management 
of  ditches  and  furrows.     Special  ditching-ploughs  of  unusual 
depth  and  reach  are  made  as  right  and  left  ploughs,  or  some- 
times to  throw  dirt  in  both  directions,  having  a  V-shaped  shear, 
thus  making  a  V-ditch  at  one  operation.     Ploughs  of  this  kind 

•are  also  arranged  in  gangs  on  sulkies. 

Corrugated  ribbed  rollers  are  employed  where  the  surface  of 
the  country  is  even  and  level,  and  for  such  crops  as  grain  and 
alfalfa.  These  consist  essentially  of  a  roller  of  the  ordinary 
form,  on  the  outer  surface  of  which  are  iron  rings  or  projections 
of  from  2  to  3  inches  in  height  and  of  about  the  same  width, 
placed  from  4  to  8  inches  apart.  These  projections  are  some- 
times V-shaped.  In  running  this  roller  over  the  surface  of  a- 
well-harrowed  field  it  leaves  small  furrows,  down  which  the 
water  runs,  thus  irrigating  the  crop  much  as  if  it  were  flooded. 

412.  Scrapers. — The  most  useful  implement  for  the  ditch- 
and  canal-maker  is  the  scraper,  of  which  there  are  many  forms 
and  with  most  of  which  engineers  are  familiar.     Two  forms 
of  scrapers  which   have   peculiar   advantages  in  ditch-making 


558 


PUMPING,    TOOLS,    AND   MAINTENANCE 


over  the  ordinary  road-scraper  are  the  Fresno  and  Buck  scrapers. 
The  latter  is  especially  useful  in  sandy  soil  with  a  low  lift  and 
short  haul,  and  cheaper  work  has  been  done  with  it  than  with 
any  other  implement.  A  common  form  of  Buck  scraper  con- 
sists of  a  working  or  frond  board  with  an  effective  length  of 
about  9  feet  and  a  height  of  22  inches.  This  board  rests  hori- 
zontally on  edge  on  the  ground  and  consists  of  two  planks  each 
2  inches  in  thickness,  below  which  is  fastened  an  iron  cutting 
edge  which  reaches  7  inches  below  (Fig.  194).  At  either  end  of 


0123 

FIG.  194. — Buck  Scraper. 


4  Feet 


the  scraper  is  a  cam-shaped  roller  4  inches  in  height,  on  which 
the  scraper  is  turned  over.  This  board  is  fastened  at  the  back 
to  a  tailboard  3  feet  9  inches  in  length,  on  which  the  driver  stands, 
and  is  drawn  forward  by  from  two  to  four  horses,  the  scraper 
being  dumped  by  the  driver  merely  stepping  off  the  tailboard, 
the  forward  pull  upsetting  it.  This  implement  handles,  a  load 
of  from  i  to  ij  cubic  yards,  while  its  average  daily  capacity  is 
about  130  cubic  yards.  For  two  horses  a  scraper  of  this  form 
is  rarely  made  over  6  feet  in  length,  and  the  angle  of  the  face- 
board  to  the  ground  is  about  28  degrees,  and  is  regulated  by 
the  attachment  to  the  tailboard.  The  Fresno  scraper  is  most 
satisfactory  in  handling  tough  earth  too  heavy  to  be  handled 
by  a  Buck  scraper,  and  which  would  even  give  trouble  to  a  road- 
scraper.  This  implement  is  usually  drawn  by  four  horses  and 


GRADING-    AND    EXCAVATING-MACHINES 


559 


handles  about   100  cubic  yards  a  day,  each  load  averaging  a 
third  of  a  cubic  yard. 

413.  Grading-  and  Excavating-machines. — Several  of  the 
road-grading  machines  give  great  satisfaction  in  levelling  and 
grading  land  which  is  to  be  irrigated.  The  more  useful  expedite 
the  work  of  preparing  land  for  furrow  or  flooding,  and  thus  greatly 
aid  the  operations  of  applying  water.  One  of  the  most  popular 
ditching-machines  now  employed  in  the  West  as  a  ditcher  and 
excavator  consists  of  a  series  of  gang-ploughs  suspended  on 
wheels.  An  endless  belt  or  elevator  is  attached  to  the  truck 
above  these  ploughs  in  such  manner  that  it  catches  the  dirt  turned 
up  by  them  and  deposits  it  on  the  banks  of  the  canal  (Fig.  195). 


FIG.  195. — New  Era  Excavator. 

This  machine  requires  from  eight  to  twelve  horses  and  three  men 
to  operate  it,  its  maximum  lift  being  about  10  feet,  while  each 
plough  makes  a  furrow  12  inches  wide  and  6  inches  deep.  These 
machines  have  attained  an  average  capacity  of  100  cubic  yards 
per  linear  mile  and  handle  about  1000  cubic  yards  in  a  day's  run. 
They  are  of  use  not  only  in  excavating  and  building  canals,  but 
also  in  building  low  earth  embankments  for  storage-reservoirs. 
An  elaborate  great  canal  excavator  used  in  California  consists 


560  PUMPING,    TOOLS,    AND   MAINTENANCE 

of  a  bridge-truss  supported  on  wheels  running  on  rails  on  either 
bank  of  the  canal.  This  deck  truss  has  on  it  a  track  on  which 
the  engine-house  and  machinery  travel  back  and  forth  across  the 
canal,  and  the  excavator  consists  of  a  dredging  arm  carrying  an 
endless  chain  of  buckets.  The  material  brought  up  by  these  is 
deposited  on  one  of  two  endless  belt-carriers  running  on  booms 
which  dump  it  on  either  spillbank.  The  engineer  can  cause  the 
excavator  to  move  across  the  canal  on  the  truss  bridge,  or  can 
raise  or  lower  the  excavating  arm  carrying  the  buckets,  causing 
these  to  move  forward  and  perform  their  work.  There  are 
twenty-six  of  these  buckets,  each  having  a  capacity  of  £  cubic 
yard,  and  the  apparatus  will  excavate  3000  cubic  yards  a  day  in 
hardpan.  In  earth  this  machine  has  excavated  from  4000  to 
5000  cubic  yards  a  day,  at  an  average  cost  of  7  cents  per  cubic 
yard. 

Dredges  of  various  forms  are  employed  on  the  larger  canals 
to  remove  silt  which  may  be  deposited  in  them,  and  to  repair 
and  straighten  banks  which  have  been  cut  down  or  eroded  by 
the  action  of  the  water.  Such  dredges  are  usually  employed 
on  scows  or  flatboats,  and  are  operated  by  small  steam-engines, 
being  similar  in  design  and  in  construction  to  the  ordinary  dredge 
employed  in  river  and  harbor  work  and  in  like  operations.  A 
small  dredge  which  has  recently  been  employed  on  irrigation 
canals  has  a  draught  of  only  15  inches  a  single  bucket,  and  can 
excavate  from  2  feet  above  the  water-line  down  to  8  feet  below 
it,  delivering  either  to  a  shore  conveyor  or  to  scows.  A  larger 
dredge  of  similar  construction  has  a  3 -foot  draught  and  exca- 
vates as  much  as  70  cubic  yards  per  hour,  delivering  it  at  a  dis- 
tance of  100  feet. 

414.  Maintenance  and  Supervision. — Careful  attention  should 
be  paid  to  the  proper  maintenance  and  the  making  of  all  needful 
repairs  on  the  lines  of  canals,  on  reservoirs,  and  other  irrigation 
works.  The  expenditure  of  an  exceedingly  small  amount  of  time 
or  money  in  repairing  an  injury  to  canal  banks  or  other  works 
may  prevent  great  destruction  of  life  and  property  consequent 
on  an  injury  to  the  reservoir  or  canal  system.  In  order  that  these 
repairs  may  be  intelligently  made,  and  that  damage  to  the  canal 


SOURCES    OF    IMPAIRMENT   OF    IRRIGATION    WORKS       561 

property  may  be  discovered  in  time,  a  suitable  system  of  super- 
vision must  be  inaugurated  upon  the  completion  of  construction. 
Such  a  system  should  include  an  engineer,  a  superintendent,  and 
patrolmen. 

Careful  and  frequent  inspection  must  be  made  of  earthen 
reservoir  embankments  or  masonry  dams  to  detect  any  sign  of 
increased  leakage.  Cracks  in  the  latter  may  be  filled  with  Port- 
land-cement grout  under  pressure,  and  leaks  by  plastering  with 
rich  cement  mortar.  If  seepage  water  through  an  earth  em- 
bankment is  muddy  it  indicates  serious  leakage.  This  may 
be  repaired  by  drawing  off  the  water  and  puddling  at  the  upper 
point  of  leakage,  or  even  by  excavating  a  pit  in  the  embankment 
from  above  and  puddling  and  well  bonding  with  new  material. 
When  reservoirs  become  silten  this  must  be  removed  by  ex- 
cavating, washing,  or  sluicing.  Waste  weirs  must  be  kept  clear 
to  their  full  capacities,  as  must  undersluices,  and  the  gates  of 
the  latter  must  be  kept  in  good  working  order. 

415.  Sources  of  Impairment  of  Irrigation  Works. — These 
are: 

1.  Erosion  of  the  inner  slope  of  the  banks  by  the  canal  water. 

2.  Filling  of  the  canal  channel  or  reservoir  from  deposition 
of  sediment. 

3.  Erosion  of  the  outer  banks  due  to  storm  and  flood  waters. 

4.  Damage  from  cattle,   horses,   and  trespassers  destroying 
the  banks,  channel,  and  dams  by  walking  over  them. 

5.  Injury  or  destruction  to  the  head  works,  regulators,   es- 
capes, or  wasteways  by  floods. 

6.  Incendiarism. 

7.  Decay  in  timbers  forming  structures. 

8.  Destruction  of  earth-banks  due  to  burrowing  by  gophers. 

9.  Injury  from  growth  of  weeds  or  water  plants  choking  the 
channel,  and  thus  diminishing  its  discharge. 

The  first  and  second  causes  of  impairment  may  be  dimin- 
ished by  the  use  of  intelligent  engineering  skill  in  the  alignment 
and  construction  of  the  canals,  and  by  the  vigilance  of  patrols 
in  discovering  indications  of  erosion  and  rectifying  them.  If 
the  amount  of  sediment  deposited  is  large,  it  will  have  to  be 

36 


562  PUMPING,    TOOLS,    AND    MAINTENANCE 

removed  by  dredges  or  scrapers,  and  such  changes  will  have  to 
be  made  in  the  headworks  or  slope  of  the  canal  or  by  the  in- 
sertion of  flushing  escapes  as  to  rectify  them.  Little  injury 
should  be  caused  the  outer  banks  of  the  canal  by  storm  waters 
if  the  canal  is  properly  aligned  and  ample  provisions  made  for 
the  passage  of  drainage  channels.  Injury  due  to  rain  falling  on 
the  banks  may  be  reduced  to  a  minimum  by  the  encourage- 
ment of  the  growth  of  grass  and  trees. 

Damage  to  the  canal  from  the  fifth  and  seventh  causes  may 
be  provided  against  in  the  construction  by  building  the  structure 
of  some  permanent  material  as  masonry  or  iron,  and  during 
operation  by  proper  supervision  and  repairs  of  the  weakened 
part.  Much  damage  may  result  from  the  burrowing  of  gophers 
and  moles.  This  can  only  be  prevented  by  careful  supervision, 
the  discovery  of  the  holes,  and  the  destruction  of  the  pests.  The 
discharge  of  a  canal  may  be  considerably  reduced  by  the  growth 
of  aquatic  plants  and  willows  along  the  banks.  This  is  to  be 
prevented  only  by  pulling  up  or  mowing  the  brush  or  by  de- 
stroying it  by  fire  when  the  canal  is  emply. 

416.  Inspection. — In  order  that  the  supervision  and  inspec- 
tion of  works  may  be  properly  performed,  the  canal  line  should 
be  divided  into  a  number  of  sections,  each  of  which  should  be 
patrolled  by  a  ditch-rider,  while  the  whole  should  be  in  charge 
of  a  superintendent.     Where  the  line  is  long,  telephone  com- 
munication should  be  had  from  each  section  to  the  main  office 
of  the  engineer  and  superintendent.     In  addition  to  this,  supplies 
of  lumber,  cement,  gravel,  or  other  building  material  should  be 
placed  at  each  bridge,  escape,  or  other  work  on  the  canal,  and 
by  this  means  any  damage  inflicted  may  be  immediately  repaired 
by  the  patrol,  or  he  may  telephone  to  headquarters  for  further 
assistance  and  proper  advice.     The  length  of  a  division  of  the 
patrol  should  be  regulated  by  the  number  of  irrigation  outlets 
and  the  character  of  the  works,  and  they  should  be  of  such  length 
that  every  portion  can  be  visited  daily. 

417.  Works  of  Reference.     Pumping  Machinery. 

BALE,  M.  Powis.     Pumps  and  Pumping.     Crosby,  Lockwood   &  Son,  London, 
1880. 


WORKS  OF  REFERENCE.   PUMPING  MACHINERY   563 

BARR,  W.  M.     Pumping  Machinery.     J.  B.  Lippincott  &  Co.,  Philadelphia,  1893. 
BJORLING,  PHILIP  R.     Water  on  Hydraulic  Motors.     E.   &  F.  N.  Spon,  London, 

1894. 

BOVEY,  H.  T.     A  Treatise  on  Hydraulics.     John  Wiley  &  Sons,  New  York,  1895. 
BRESSE,  M.,    trans,  by  F.  A.  MAHAN.     Water-wheels  or  Hydraulic  Motors.     John 

Wiley   &  Sons,  New  York,  1876. 
FANNING,   J.   T.     Water-supply  Engineering.     D.   Van  Nostrand    &  Co.,   New 

York,  1889. 
GRIFFITHS,  J.  A.     Windmills  for  Raising  Water.     Proc.  Inst.  C.  E.,  vol.  cxix,  No. 

2672,  London,  1895. 
HUGHES,   SAMUEL.     A   Treatise  on   Water-works.     Crosby,   Lockwood    &:   Son, 

London,  1882. 

MAHAN,  F.  A.     Water-wheels.     E.   &  F.  N.  Spon,  New  York. 
MURPHY,   E.   C.     The  Windmill;    its  Efficiency  and  Economic  Use.     2   Parts. 

Water  Supply  Papers  Nos.  41  and  42.     U.  S.  Geological  Survey,  Washington, 

D.  C.,  1901. 

RONNA,  A.     Les  Irrigations.     Firmin-Didot  et  Cie.,  Paris. 
TROWBRIDGE,  W.  P.     Turbine  Water-wheels.     D.  Van  Nostrand    &  Co.,  New 

York. 
TURNEAURE,  F.  E.,  and  RUSSELL,  H.  L.     Public  Water  Supplies.     John  Wiley 

&  Sons,  New  York,  1901. 
WEISBACH,  P.   J.,  and  Du  Bois,  A.  JAY.     Hydraulics  and  Hydraulic  Motors. 

John  Wiley  &  Sons,  New  York,  1889. 
WILSON,  HERBERT  M.     Pumping  Water  for  Irrigation.     Water  Supply  Paper  No. 

i.     U.  S.  Geological  Survey,  Washington,  D.  C.,  1896. 
WOLFF,  ALFRED  R.     The  Windmill  as  a  Prime  Mover.     John  Wiley    &  Sons 

New  York,  1890. 


CHAPTER  XX 

RECLAMATION    SERVICE    OF    THE    UNITED    STATES 

418.  The  Reclamation  Law. — The  full  text  of  the  reclama- 
tion law  dated  June  17,  1902,*  is  as  follows: 

AN  ACT  Appropriating  the  receipts  from  the  sale  and  disposal  of  public  lands  in  certain 
States  and  Territories  to  the  construction  of  irrigation  works  for  the  reclamation  of 
arid  lands. 

Be  it  enacted  by  the  Senate  and  House  of  Representatives  oj  the  United  States 
0}  America  in  Congress  assembled,  That  all  moneys  received  from  the  sale  and 
disposal  of  public  lands  in  Arizona,  California,  Colorado,  Idaho,  Kansas,  Mon- 
tana, Nebraska,  Nevada,  New  Mexico,  North  Dakota,  Oklahoma,  Oregon,  South 
Dakota,  Utah,  Washington,  and  Wyoming,  beginning  with  the  fiscal  year  ending 
June  thirtieth,  nineteen  hundred  and  one,  including  the  surplus  of  fees  and  com- 
missions in  excess  of  allowances  to  registers  and  receivers,  and  excepting  the  five 
per  centum  of  the  proceeds  of  the  sales  of  public  lands  in  the  above  States  set  aside 
by  law  for  educational  and  other  purposes,  shall  be,  and  the  same  are  hereby, 
reserved,  set  aside,  and  appropriated  as  a  special  fund  in  the  Treasury  to  be  known 
as  the  "reclamation  fund,"  to  be  used  in  the  examination  and  survey  for  and  the 
construction  and  maintenance  of  irrigation  works  for  the  storage,  diversion,  and 
development  of  waters  for  the  reclamation  of  arid  and  semi-arid  lands  in  the  said 
States  and  Territories,  and  for  the  payment  of  all  other  expenditures  provided 
for  in  this  Act:  Provided,  That  in  case  the  receipts  from  the  sale  and  disposal  of 
public  lands  other  than  those  realized  from  the  sale  and  disposal  of  lands  referred 
to  in  this  section  are  insufficient  to  meet  the  requirements  for  the  support  of  agri- 
cultural colleges  in  the  several  States  and  Territories,  under  the  Act  of  August 
thirtieth,  eighteen  hundred  and  ninety,  entitled  "An  Act  to  apply  a  portion  of  the 
proceeds  of  the  public  lands  to  the  more  complete  endowment  and  support  of  the 
colleges  for  the  benefit  of  agriculture  and  the  mechanic  arts,  established  under 
the  provisions  of  an  Act  of  Congress  approved  July  second,  eighteen  hundred  and 
sixty-two,"  the  deficiency,  if  any,  in  the  sum  necessary  for  the  support  of  the  said 
colleges  shall  be  provided  for  from  any  moneys  in  the  Treasury  not  otherwise 
appropriated. 

SEC.  2.  That  the  Secretary  of  the  Interior  is  hereby  authorized  and  directed 
to  make  examinations  and  surveys  for,  and  to  locate  and  construct  as  herein  pro- 
vided, irrigation  works  for  the  storage,  diversion,  and  development  of  waters, 
including  artesian  wells,  and  to  report  to  Congress  at  the  beginning  of  each  regular 
session  as  to  the  results  of  such  examinations  and  surveys,  giving  estimates  of  cost 
of  all  contemplated  works,  the  quantity  and  location  of  the  lands  which  can  be 
irrigated  therefrom,  and  all  facts  relative  to  the  practicability  of  each  irrigation 

*Stat.  L.,  vol.  xxxii.,  p.  388. 
564 


THE   RECLAMATION   LAW  565 

project;  also  the  cost  of  works  in  process  of  construction  as  well  as  of  those  which 
have  been  completed. 

SEC.  3.  That  the  Secretary  of  the  Interior  shall,  before  giving  the  public  notice 
provided  for  in  section  four  of  this  Act,  withdraw  from  public  entry  the  lands 
required  for  any  irrigation  works  contemplated  under  the  provisions  of  this  Act, 
and  shall  restore  to  public  entry  any  of  the  lands  so  withdrawn  when,  in  his  judg- 
ment, such  lands  are  not  required  for  the  purposes  of  this  Act;  and  the  Secretary 
of  the  Interior  is  hereby  authorized,  at  or  immediately  prior  to  the  time  of  begin- 
ning the  surveys  for  any  contemplated  irrigation  works,  to  withdraw  from  entry, 
except  under  the  homestead  laws,  any  public  lands  believed  to  be  susceptible  of 
irrigation  from  said  works:  Provided,  That  all  lands  entered  and  entries  made 
under  the  homestead  laws  within  areas  so  withdrawn  during  such  withdrawal 
shall  be  subject  to  all  the  provisions,  limitations,  charges,  terms  and  conditions  of 
this  Act;  that  said  surveys  shall  be  prosecuted  diligently  to  completion,  and  upon 
the  completion  thereof,  and  of  the  necessary  maps,  plans,  and  estimates  of  cost, 
the  Secretary  of  the  Interior  shall  determine  whether  or  not  said  project  is  practi- 
cable and  advisable,  and  if  determined  to  be  impracticable  or  unadvisable  he  shall 
thereupon  restore  said  lands  to  entry;  that  public  lands  which  it  is  proposed  to 
irrigate  by  means  of  any  contemplated  works  shall  be  subject  to  entry  only  under 
the  provisions  of  the  homestead  laws  in  tracts  of  not  less  than  forty  nor  more  than 
one  hundred  and  sixty  acres,  and  shall  be  subject  to  the  limitations,  charges,  terms, 
and  conditions  herein  provided:  Provided,  That  the  commutation  provisions  of 
the  homestead  laws  shall  not  apply  to  entries  made  under  this  Act. 

SEC.  4.  That  upon  the  determination  by  the  Secretary  of  the  Interior  that  any 
irrigation  project  is  practicable,  he  may  cause  to  be  let  contracts  for  the  construc- 
tion of  the  same,  in  such  portions  or  sections  as  it  may  be  practicable  to  construct 
and  complete  as  parts  of  the  whole  project,  providing  the  necessary  funds  for  such 
portions  or  sections  are  available  in  the  reclamation  fund,  and  thereupon  he  shall 
give  public  notice  of  the  lands  irrigable  under  such  project,  and  limit  of  area  per 
entry,  which  limit  shall  represent  the  acreage  which,  in  the  opinion  of  the  Secretary, 
may  be  reasonably  required  for  the  support  of  a  family  upon  the  lands  in  question; 
also  of  the  charges  which  shall  be  made  per  acre  upon  the  said  entries,  and  upon 
lands  in  private  ownership  which  may  be  irrigated  by  the  waters  of  the  said  irriga- 
tion project,  and  the  number  of  annual  installments,  not  exceeding  ten,  in  which 
such  charges  shall  be  paid  and  the  time  when  such  payments  shall  commence. 
The  said  charges  shall  be  determined  with  a  view  of  returning  to  the  reclamation 
fund  the  estimated  cost  of  construction  of  the  project,  and  shall  be  apportioned 
equitably:  Provided,  That  in  all  construction  work  eight  hours  shall  constitute  a 
day's  work,  and  no  Mongolian  labor  shall  be  employed  thereon. 

SEC.  5. — That  the  entryman  upon  lands  to  be  irrigated  by  such  works  shall, 
in  addition  to  compliance  with  the  homestead  laws,  reclaim  at  least  one-half  of 
the  total  irrigable  area  of  his  entry  for  agricultural  purposes,  and  before  receiving 
patent  for  the  lands  covered  by  his  entry  shall  pay  to  the  Government  the  charges 
apportioned  against  such  tract,  as  provided  in  section  four.  No  right  to  the  use 
of  water  for  land  in  private  ownership  shall  be  sold  for  a  tract  exceeding  one  hun- 
dred and  sixty  acres  to  any  one  landowner,  and  no  such  sale  shall  be  made  to  any 
landowner  unless  he  be  an  actual  bona  fide  resident  on  such  land,  or  occupant 
thereof,  residing  in  the  neighborhood  of  said  land,  and  no  such  right  shall  per- 
manently attach  until  all  payments  therefor  are  made.  The  annual  installments 
shall  be  paid  to  the  receiver  of  the  local  land  office  of  the  district  in  which  the 


566  RECLAMATION    SERVICE 

land  is  situated,  and  a  failure  to  make  any  two  payments  when  "due  shall  render 
the  entry  subject  to  cancellation,  with  the  forfeiture  of  all  rights  under  this  Act, 
as  well  as  of  any  moneys  already  paid  thereon.  All  moneys  received  from  the 
above  sources  shall  be  paid  into  the  reclamation  fund.  Registers  and  receivers 
shall  be  allowed  the  usual  commissions  on  all  moneys  paid  for  lands  entered  under 
this  Act. 

SEC.  6.  That  the  Secretary  of  the  Interior  is  hereby  authorized  and  directed  to 
use  the  reclamation  fund  for  the  operation  and  maintenance  of  all  reservoirs  and 
irrigation  works  constructed  under  the  provisions  of  this  Act:  Provided,  That 
when  the  payments  required  by  this  Act  are  made  for  the  major  portion  of  the 
lands  irrigated  from  the  waters  of  any  of  the  works  herein  provided  for,  then  the 
management  and  operation  of  such  irrigation  works  shall  pass  to  the  owners  of 
the  lands  irrigated  thereby,  to  be  maintained  at  their  expense  under  such  form  of 
organization  and  under  such  rules  and  regulations  as  may  be  acceptable  to  the 
Secretary  of  the  Interior:  Provided,  That  the  title  to  and  the  management  and 
operation  of  the  reservoirs  and  the  works  necessary  for  their  protection  and  opera- 
tion shall  remain  in  the  Government  until  otherwise  provided  by  Congress. 

SEC.  7.  That  where,  in  carrying  out  the  provisions  of  this  Act,  it  becomes  neces- 
sary to  acquire  any  rights  or  property,  the  Secretary  of  the  Interior  is  hereby  au- 
thorized to  acquire  the  same  for  the  United  States  by  purchase  or  by  condemna- 
tion under  judicial  process,  and  to  pay  from  the  reclamation  fund  the  sums  which 
may  be  needed  for  that  purpose,  and  it  shall  be  the  duty  of  the  Attorney-General 
of  the  United  States  upon  every  application  of  the  Secretary  of  the  Interior,  under 
this  Act,  to  cause  proceedings  to  be  commenced  for  condemnation  within  thirty 
days  from  the  receipt  of  the  application  at  the  Department  of  Justice. 

SEC.  8.  That  nothing  in  this  Act  shall  be  construed  as  affecting  or  intended  to 
affect  or  to  in  any  way  interfere  with  the  laws  of  any  State  or  Territory  relating 
to  the  control,  appropriation,  use,  or  distribution  of  water  used  in  irrigation,  or 
any  vested  right  acquired  thereunder,  and  the  Secretary  of  the  Interior,  in  carry- 
ing out  the  provisions  of  this  Act,  shall  proceed  in  conformity  with  such  laws,  and 
nothing  herein  shall  in  any  way  affect  any  right  of  any  State  or  of  the  Federal 
Government  or  of  any  landowner,  appropriator,  or  user  of  water  in,  to,  or  from 
any  interstate  stream  or  the  waters  thereof-  Provided,  That  the  right  to  the  use 
of  water  acquired  under  the  provisions  of  this  Act  shall  be  appurtenant  to  the 
land  irrigated,  and  beneficial  use  shall  be  the  basis,  the  measure,  and  the  limit  of 
the  right. 

SEC.  9.  That  it  is  hereby  declared  to  be  the  duty  of  the  Secretary  of  the  Interior 
in  carrying  out  the  provisions  of  this  Act,  so  far  as  the  same  may  be  practicable 
and  subject  to  the  existence  of  feasible  irrigation  projects,  to  expend  the  major 
portion  of  the  funds  arising  from  the  sale  of  public  lands  within  each  State  and 
Territory  hereinbefore  named  for  the  benefit  of  arid  and  semi-arid  lands  within 
the  limits  of  such  State  or  Territory:  Provided,  That  the  Secretary  may  tempo- 
rarily use  such  portion  of  said  funds  for  the  benefit  of  arid  or  semi-arid  lands  in 
any  particular  State  or  Territory  hereinbefore  named  as  he  may  deem  advisable, 
but  when  so  used  the  excess  shall  be  restored  to  the  fund  as  soon  as  practicable, 
to  the  end  that  ultimately,  and  in  any  event,  within  each  ten-year  period  after  the 
passage  of  this  Act,  the  expenditures  for  the  benefit  of  the  said  States  and  Terri- 
tories shall  be  equalized  according  to  the  proportions  and  subject  to  the  conditions 
as  to  practicability  and  feasibility  aforesaid. 

SEC.   10.  That  the  Secretary  of  the  Interior  is  hereby  authorized  to  perform 


SCOPE    OF   RECLAMATION    LAW  567 

any  and  all  acts,  and  to  make  such  rules  and  regulations  as  may  be  necessary  and 
proper  for  the  purpose  of  carrying  the  provisions  of  this  Act  into  full  force  and 
effect. 

419.  Scope  of  Reclamation  Law. — The  first  step  in  any  action 
taken  under  the  law  is  a  request  from  the  engineers  of  the  recla- 
mation service,  made  through  the  head  of  the  organization,  the 
Director,  to  the  Secretary  of  the  Interior,  for  the  withdrawal  from 
entry  of  certain  specified  lands  with  a  view  to  their  examination 
in  the  field,  in  order  to  determine  the  practicability  of  construct- 
ing irrigation  works  for  reclaiming  them.  When  this  request  is 
approved  by  the  Secretary  of  the  Interior,  the  proper  steps  are 
taken,  by  the  General  Land  Office,  for  the  withdrawal  of  the 
lands,  through  the  local  land  office  for  the  district  in  which  they 
are  located.  Thereafter  no  entries  will  be  allowed  except,  under 
the  provisions  of  the  homestead  law,  as  modified  by  the  limitations 
and  conditions  of  the  act.  In  accordance  therewith  they  may  be 
limited  to  an  area  as  small  as  40  acres,  and  will  not  be  subject  to 
the  commutation  provisions  of  the  homestead  law.  The  entry- 
man  may,  therefore,  be  required  to  reduce  the  area  of  his  entry 
to  such  limit  as  in  the  opinion  of  the  Secretary  of  the  Interior  may 
be  reasonably  required  for  the  support  of  a  family,  and  will  be 
called  upon  to  pay  the  charges  per  acre  which  may  be  determined 
on  in  not  more  than  ten  annual  installments. 

As  soon  as  possible  after  such  withdrawal,  engineers  are 
instructed  to  make  the  survey  of  the  lands  of  proposed  canals 
and  reservoirs;  also  to  conduct  necessary  engineering  investi- 
gations concerning  the  water-supply  and  the  conditions  under 
which  the  construction  will  be  carried  on.  Upon  the  comple- 
tion of  this  work  the  results  are  summarized  and  submitted  to 
the  Secretary  of  the  Interior,  with  such  recommendations  as 
may  be  deemed  advisable  by  the  Director,  together  with  maps, 
plans,  and  estimates  of  cost. 

It  then  becomes  the  duty  of  the  Secretary  of  the  Interior  to 
determine  whether  or  not  such  project  is  practicable  and  advis- 
able. If  determined  to  be  impracticable  or  inadvisable,  he  re- 
stores to  the  public  domain  the  lands  withdrawn,  and  they  be- 
come subject  to  the  public-land  laws,  as  if  such  withdrawal  had 


568  RECLAMATION    SERVICE 

never  been  made.  If  the  project  is  approved  by  the  Secretary 
of  the  Interior,  he  may  cause  contracts  to  be  let  for  the  construc- 
tion of  the  proposed  works,  either  as  a  whole  or  for  such  portion 
or  section  as  will  constitute  a  complete  system,  if  it  should  be 
deemed  best  not  to  undertake  the  entire  project  at  that  time. 
He  will  thereupon  give  public  notice  of  the  land  which  may  be 
reclaimed  thereunder,  and  of  the  particular  limitations  contem- 
plated by  the  law  as  to  area,  cost,  number  of  installments,  date 
of  payments,  etc. 

As  soon  as  it  shall  be  possible  to  furnish  water  for  the  irri- 
gation of  any  particular  portion  of  the  lands  involved,  the  entry- 
men  thereon  will  be  allowed  to  take  the  water;  and  as  construc- 
tion progresses  additional  lands  will  be  supplied  from  time  to 
time. 

When  payments  have  been  made  in  full  for  the  major  portion 
of  the  lands  irrigable  under  any  system,  the  management  and 
operation  of  the  irrigation  works  will  pass  to  the  owners  of  the 
land  irrigated  therefrom,  to  be  maintained  at  their  expense, 
under  such  form  of  organization  and  under  such  rules  and  regu- 
lations as  may  be  acceptable  to  the  Secretary  of  the  Interior; 
it  is  provided,  however,  that  the  title  to  the  reservoirs  and  the 
works  necessary  for  their  protection  and  operation  shall  remain 
in  the  Government,  and  that  they  shall  continue  under  the  con- 
trol and  management  of  the  Government  unless  otherwise  pro- 
vided by  Congress. 

The  examination  of  the  title  to  the  lands  involved  in  each 
irrigation  project  must  be  made  before  construction  can  begin 
in  order  to  determine  how  much  of  each  tract  is  public  or  pri- 
vate land.  In  connection  with  the  right  of  way  for  canals  to  be 
constructed  by  the  reclamation  service,  by  decisions  of  the  Secre- 
tary of  the  Interior  of  October  5,  1893  (Decisions  of  the  Depart- 
ment of  the  Interior  Relating  to  Public  Lands,  Vol.  17,  page 
521),  it  has  been  held  that  all  lands  entered  subsequent  to  Octo- 
ber 2,  1888,  are  subject  to  a  right  of  way  for  ditches  or  canals 
constructed  by  the  authority  of  the  United  States,  in  pursuance 
of  an  Act  of  August  30,  1890  (26  Stat.  L.,  p.  391). 

In  each  project  for  reclamation  there  are  involved  tracts  of 


WATER   USERS'    ASSOCIATION  569 

lands  under  private  ownership  and  waters  claimed  by  individuals, 
and  it  is  necessary  to  make  a  careful  examination  of  their  charac- 
ter, the  title,  etc.  In  obtaining  this  information,  it  is  necessary 
to  discover  how  much  water  was  being  used  per  acre  of  land 
irrigated,  and  to  report  how  much  land  was  irrigated  and  from 
what  sources. 

The  use  of  public  lands  for  right  of  way  for  canals  and  laterals 
constructed  by  the  reclamation  service  is  provided  for  by  the 
Act  of  October  2,  1888  (25  Stat.  L.,  526).  There  is  also  a  reser- 
vation of  right  of  way  for  canals  constructed  by  the  United  States 
affecting  all  lands  disposed  of  subsequent  to  that  date. 

420.  Water  Users'  Association. — When  it  appears  probable 
that  any  particular  project  will  be  carried  into  effect,  steps  are 
taken  looking  toward  the  organization  of  an  association  of  people 
owning  land  under  the  project.  The  object  of  this  association 
is  to  secure  prompt  and  effective  dealing  between  the  Secretary 
of  the  Interior  and  the  water  users.  The  latter  should  have  a 
common  agent,  as  officers,  with  whom  business  may  be  trans- 
acted. 

The  first  association  formed  to  carry  out  the  purpose  of  the 
law  is  the  Salt  River  Valley  Water  Users'  Association,  the  articles 
of  incorporation  of  which  were  prepared  after  long  discussion 
and  consultation  with  legal  advisors,  engineers,  and  landowners. 
In  forming  such  associations  among  other  points  to  be  considered 
is  that  they  shall  be  organized  simply  for  the  purpose  of  carrying 
out  the  provisions  of  the  law  and  not  for  speculative  purposes. 
They  should  be  constituted  solely  for  the  purpose  of  acquiring, 
maintaining,  and  operating  the  irrigation  works  at  their  own 
expense.  The  necessity  for  the  formation  of  these  associations 
results  from  each  owner  of  land  having  his  own  preference  regard- 
ing details  of  management,  which  should  be  fully  discussed  in 
public  meetings  by  all  interested  water  users,  that  a  majority 
view  may  be  presented  to  the  officers  of  the  reclamation  service. 
This  is  particularly  true  concerning  details  of  water  distribution, 
while  on  the  other  hand  the  ownership,  management,  and  opera- 
tion of  the  storage  works  and  main  diversion  canals  remain  by 
law  in  the  hands  of  the  reclamation  service. 


570  RECLAMATION    SERVICE 

The  members  of  the  Salt  River  Valley  Water  Users'  Association 
at  the  time  of  its  incorporation  in  1903,  pledged  their  lands  to  the 
amount  of  200,000  acres  for  the  return  to  the  United  States  of 
the  cost  of  the  reservoir  and  auxiliary  works.  A  contract  was 
approved  by  the  Secretary  of  the  Interior  and  later  adopted  by 
the  Association  early  in  1904,  which  reads  as  follows: 

These  articles  of  agreement,  made  and  entered  into  this  25th  day  of  June, 
1904,  by  and  between  the  United  States  of  America,  acting  in  this  behalf  by  Ethan 
A.  Hitchcock,  Secretary  of  the  Interior,  party  of  the  first  part,  and  the  Salt  River 
Valley  Water  Users'  Association,  a  corporation  duly  organized  and  existing  under 
the  laws  of  the  Territory  of  Arizona,  party  of  the  second  part,  their  successors  and 
assigns,  witnesseth: 

That  whereas  the  Salt  River  Valley  Water  Users'  Association  is  a  corporation 
organized  and  existing  under  the  laws  of  the  Territory  of  Arizona  for  the  purpose 
mentioned  in  its  articles  of  incorporation,  a  copy  of  which  is  appended  to  this 
memorandum  (which  is  marked  "Articles  of  incorporation  referred  to  in  the 
attached  memorandum,  and  attested  by  the  signature  of  the  honorable  the  Secre- 
tary of  the  Interior  of  the  United  States  of  America  and  of  the  president  of  the 
Salt  River  Valley  Water  Users'  Association,  for  the  purpose  of  identification"), 
and  are  for  every  purpose  of  the  interpretation,  construction,  and  consideration  of 
this  memorandum,  and  of  the  rights  of  the  parties  hereunder,  to  be  deemed,  held, 
read  and  considered  as  if  fully  written  out  or  printed  herein,  and  deemed  a  part 
hereof. 

And  whereas  the  lands  embraced  within  the  district  of  lands  described  in  Sec- 
tion 3  of  Article  IV  of  said  articles  of  incorporation  are  naturally  desert  and  arid 
and  incapable  of  proper  cultivation  without  irrigation,  and  unless  the  waters  of 
the  Salt  and  Verde  rivers  in  Arizona  and  their  tributaries  be  impounded  and  the 
flow  thereof  otherwise  regulated  and  controlled  will,  to  a  greater  or  less  extent, 
remain  unreclaimed,  unfit  for  habitation  and  uncultivated,  in  which  condition 
they,  or  a  great  part  thereof,  are  now. 

And  whereas  the  Secretary  of  the  Interior  of  the  United  States  of  America  con- 
templates the  construction  of  certain  irrigation  works  under  the  provisions  of  an 
Act  of  Congress  entitled  "An  act  appropriating  the  receipts  from  the  sale  and 
disposal  of  public  lands  in  certain  States  and  Territories  to  the  construction  of 
irrigation  works  for  the  reclamation  of  arid  lands,"  approved  June  17,  1902,  in 
and  across  Salt  River  at  a  point  about  32  miles  up  the  course  of  said  Salt  River 
above  the  confluence  of  the  Verde  River  and  said  Salt  River,  said  point  being 
near  the  mouth  of  Tonto  Creek,  for  the  purpose  of  there  impounding  the  waters 
of  said  Salt  River  and  otherwise  regulating  and  controlling  the  flow  of  water  there- 
in, and  works  necessarily  or  conveniently  incident  thereto,  for  the  use  of  said  waters 
for  the  reclamation  of  arid  lands  along  the  course  of  said  Salt  River;  and 

Whereas  the  incorporators  of  said  Salt  River  Valley  Water  Users'  Association 
and  its  shareholders  are,  and  under  the  provisions  of  its  articles  of  incorporation 
must  be,  owners  and  occupants  of  land  and  the  appropriators  of  water  from  said 
Salt  River  and  said  Verde  River  and  their  respective  tributaries  for  the  irrigation 


WATER    USERS'    ASSOCIATION  571 

thereof,  and  in  addition  thereto  such  incorporators,  shareholders,  and  constitu- 
ents, and  their  assigns  or  successors,  must  initiate  rights  to  the  use- of  water  from 
the  said  proposed  irrigation  works,  to  be  constructed  by  the  said  Secretary  of  the 
Interior,  as  soon  as  such  rights  may  be  initiated,  and  thereafter  complete  the 
acquisition  thereof  in  the  manner  and  upon  the  terms  and  conditions  to  be 
prescribed  therefor  by  the  Secretary  of  the  Interior,  which  rights  shall  be,  and 
thereafter  continue  to  be,  forever  appurtenant  to  designated  lands  owned  by  such 
shareholders  and  constituent  members;  and 

Whereas  neither  the  relative  priority  and  extent  of  the  individual  appropria- 
tions of  such  water  heretofore  made  by  said  incorporators,  shareholders,  and  con- 
stituent members,  nor  the  proportion  of  the  entire  waters  of  said  water  courses 
that  has  been  in  the  aggregate  appropriated  by  them,  and  which  are  now  vested 
rights,  have  been  ascertained  or  determined,  but  said  incorporators,  shareholders, 
and  constituent  members  of  said  association  have  agreed  among  themselves,  by 
the  terms  and  provisions  of  said  articles  of  incorporation,  upon  the  rules  and  prin- 
ciples by  and  upon  which  the  relative  priority  and  the  extent  of  their  several  ap- 
propriations and  vested  rights  to  the  use  of  such  waters  shall  be  determined. 

r.  Now,  therefore,  if  the  said  Secretary  of  the  Interior  shall  authorize  and 
shall  cause  the  construction  of  said  irrigation  works,  then  in  the  determination  of 
the  relative  rights  of  the  shareholders  of  said  association,  and  of  their  respective 
rights  to  the  use  of  water  acquired  from  the  Government  under  said  Act  of  Con- 
gress, the  rules  and  principles  set  out  in  said  articles  of  incorporation  for  such  de- 
termination shall  be  deemed  the  established  rules  and  principles  for  that  purpose. 

2.  That  only  those  who  are,  or  who  may  become  members  of  said  association, 
under  the  provisions  of  its  articles  of  incorporation,  shall  be  accepted  as  entrymen 
or  applicants  for  rights  to  the  use  of  water  impounded,  developed,  or  the  supply  of 
which  is  or  may  be  regulated  or  controlled  by  said  proposed  irrigation  works. 

3.  That  the  aggregate  amount  of  such  rights  to  be  issued  shall  in  no  event 
exceed  the  number  of  acres  of  land  capable  of  irrigation  by  the  total  amount  of 
water  available  for  the  purpose,  being  (i)  the  amount  now  appropriated  by  the 
shareholders  of  said  association,  and  (2)  the  amount  to  be  impounded  and  de- 
veloped in  excess  of  the  water  now  appropriated.     The  Secretary  of  the  Interior 
shall  determine  the  number  of  acres  so  capable  of  such  irrigation  as  aforesaid,  his 
determination  to  be  made  upon  due  and  expert  consideration  of  all  available  data, 
and  to  be  based  upon  and  measured  and  limited  by  the  beneficial  use  of  water. 

4.  That  the  payments  for  the  reservoir  rights  to  be  issued  to  the  shareholders 
of  said  association,  under  the  provisions  of  said  Act  of  Congress,  shall  be  divided 
into  not  less  than  ten  equal  annual  payments,  the  first  whereof  shall  be  payable 
at  the  time  of  the  completion  of  said  proposed  reservoir,  or  within  a  reasonable 
time  thereafter,  and  after  due  notice  thereof  by  the  Secretary  of  the  Interior  to  the 
association.     The   cost  of  said   proposed   irrigation   works  shall   be   apportioned 
equally  per  acre  among  those  acquiring  such  rights. 

5.  The  said  Salt  River  Valley  Water  Users'  Association  agrees  that  it  will 
promptly  collect  or  require  prompt  payment  in  such  manner  as  the  Secretary  of 
the  Interior  may  direct,  and  hereby  guarantees  the  payments  for  that  part  of  the 
cost  of  the  irrigation   works  which  shall  be  apportioned  by  the  Secretary  of  the 
Interior  to  its  shareholders,  and  promptly  pay  the  sums  collected  by  it  to  the  re- 
ceiver of  the  local  land  office  for  the  district  in  which  said  lands  are  situate;   that 


572  RECLAMATION    SERVICE 

it  will  promptly  employ  the  means  provided  and  authorized  by  the  said  articles  of 
incorporation  for  the  enforcement  of  such  collections,  and  will  not  change,  alter, 
or  amend  its  articles  of  incorporation  in  any  manner  whereby  such  means  of  col- 
lection, or  the  lien  given  to  it  by  the  shareholders  to  secure  the  payment  thereof, 
or  of  any  assessments  contemplated  or  authorized  thereby,  shall  be  impaired,  di- 
minished, or  rendered  less  effective,  without  the  consent  of  the  Secretary  of  the 
Interior. 

6.  The  United  States  shall  in  no  manner  be  responsible  for  the  sums  collected 
by  said  association  until  they  have  been  paid  into  the  hands  of  the  receiver  of  the 
local  land   office,  as   provided   by  the   law,  and  in  accordance  with  such  regula- 
tions as  may  be  prescribed  by  the  Secretary  of  the  Interior. 

7.  That  for  the  purpose  of  enforcing  said  collections,  the  association  will  adopt 
and  enforce  proper  by-laws,  subject  to  the  approval  of  the  Secretary  of  the  In- 
terior, and  not  change  them  so  as  to  in  anywise  impair  their  efficiency  for  said  pur- 
pose, and  will  otherwise  do  any  and  all  things  it  is  authorized  and  empowered  to 
do  in  the  premises. 

8.  That  the  association  will  adopt  and  enforce  such  rules  and  regulations  as  it 
is  authorized  by  its  articles  of  incorporation  to  adopt  and  enforce  concerning  the 
use  of  water  by  its  shareholders  and  concerning  the  administration  of  the  affairs 
of  the  association,  to  effectually  carry  out  and  promote  the  purposes  of  its  organ- 
ization, within  the  provisions  of  said  articles  of  incorporation,  which  rules  and 
regulations  shall  be  subject  to  the  approval  of  the  Secretary  of  the  Interior.     That 
if  the  association  fail  to  make  and  adopt  such  rules  and  regulations,  then  the  Secre- 
tary of  the  Interior  may  prescribe  them;    but  in  such  event  it  is  understood  that 
the  Secretary  of  the  Interior  shall  impose  no  rule  or  regulation  interfering  with 
any  vested  right  of  the  shareholders  of  the  association  as  defined  or  modified  by 
said  articles  of  incorporation. 

9.  Persons  who  are  not  now  members  of  the  association,  but  who  may  be  the 
owners  or  occupants  of  land  within  the  reservoir  district  described  in  Section  3 
of  Article  IV,  or  of  added  lands  provided  for  in  that  section  and  to  whom  rights 
to  the  use  of  water,  from  the  proposed  reservoir  or  irrigation  works,  may  be  issued, 
may,  at  the  designation  of  the  Secretary  of  the  Interior,  become  members  of  the 
association  by  subscribing  to  the  stock  thereof,  and  upon  the  compliance  with  the 
other  conditions  prescribed  for  such  membership. 

10.  It  is  understood  that  in  all  the  relations  between  the  Government  and  this 
association  and  the  members  of  the  association  the  rights  of  the  members  of  the 
association  are  to  be  defined  and  determined  and  enjoyed  by  and  under  the  pro- 
visions of  the  said  Act  of  Congress  and  of  other  Acts  of  Congress  on  the  subject 
of  the  acquisition  and  enjoyment  of  the  rights  to  use  water,  and  by  the  laws  of 
Arizona  where  not  inconsistent  therewith,  where  such  rights  have  vested,  modified, 
if  modified  at  all,  by  the  provisions  of  the  articles  of  incorporation  of  said  associa- 
tion. 

ii.  Nothing  contained  in  this  memorandum,  or  to  be  implied  from  the  fact  of 
its  execution,  shall  be  construed,  held,  or  deemed  to  be  an  approval  by  the  Secre- 
tary of  the  Interior,  nor  an  adoption  by  him,  of  the  articles  of  incorporation  of 
said  association,  in  all  their  details  as  the  form  of  organization  of  water  users  con- 
templated and  authorized  by  Section  6  of  the  said  Act  of  Congress  of  June  17, 
1902;  but  such  approval  and  adoption  is  expressly  reserved  until  the  conditions 


SPECIFICATIONS,    RECLAMATION    SERVICE  573 

authorizing  such  approval  and  adoption  prescribed  in  said  act  shall  have  arisen. 
And  when  the  Secretary  of  the  Interior  shall  make,  approve,  and  promulgate  rules 
and  regulations  for  the  administration  of  the  water  to  be  supplied  from  such  pro- 
posed irrigation  works,  such  rules  and  regulations,  and  such  modifications  thereof 
as  the  Secretary  may,  from  time  to  time,  approve  and  promulgate,  shall  be  deemed 
and  held  to  be  obligatory  upon  this  association  as  fully  and  completely,  and  to 
every  intent  and  purpose,  as  if  they  were  now  made,  approved,  promulgated,  and 
written  out  in  full  in  this  memorandum,  and  are  to  be  read  and  construed  as  if 
so  done. 

In  witness  whereof  the  undersigned  have  hereunto  subscribed  their  names  and 
affixed  their  seals  the  day  and  year  first  herein  written. 

ETHAN  A.  HITCHCOCK, 

Secretary  of  the  Interior, 

For  and  on  behalf  of  the  United  States  of  America,  party  of  the  first  part. 
[Departmental  seal.] 
Witness: 

W.  SCOTT  SMITH, 

SALT  RIVER  VALLEY  WATER  USERS'  ASSOCIATION, 

Party  of  the  second  part. 
By  B.  A.  FOWLER,  President. 

FRANK  H.  PARKER,  Secretary. 
[Corporate  seal.] 
Witness: 

JOSEPH  H.  KIBBEY, 
C.  G.  WILLIAMS. 


421.  Specifications,  Reclamation  Service. — The  following  is 
a  typical  specification: 

Specifications,  Roosevelt  Dam. 

GENERAL  CONDITIONS. 

1.  Form  of  proposal  and  signature. — The  proposal  must  be  made  on  the  form 
provided  for  that  purpose,  inclosed  in  a  sealed  envelope,  and  marked  and  addressed 
as  required  in  the  advertisement,  stating,  in  writing  and  in  figures,  the  sum  of  money 
for  which  the  bidder  proposes  to  supply  the  materials  and  perform  the  work  required 
by  the  drawings  and  specifications,  the  unit  prices,  and  the  separate  estimates  called 
for  in  the  proposal.     It  must  be  signed  with  the  full  name  and  address  of  the  bidder; 
if  a  co-partnership,  the  co-partnership  name  by  a  member  of  the  firm,  with  the  name 
and  address  in  full  of  each  member;  and  if  a  corporation,  by  an  officer  in  the  cor- 
porate name,  with  the  corporate  seal  attached  to  such  signature.     No  telegraphic 
proposal  or  telegraphic  modification  of  proposal  will  be  considered. 

2.  Proposals. — All  blank  spaces  in  the  proposal  must  be  filled  in,  and  no  change 
shall  be  made  in  the  phraseology  of  the  proposal,  or  addition  to  the  items  mentioned 
therein.     Any  conditions,  limitations,  or  provisos  attached  to  a  proposal  will  be 
liable  to  render  it  informal  and  may  cause  its  rejection.     Alterations  by  erasure  or 


574  RECLAMATION    SERVICE 

interlineation  must  be  explained  or  noted  in  the  proposal  over  the  signature  of  the 
bidder.  If  a  bidder  wishes  to  withdraw  his  proposal  he  may  do  so  before  the  time 
fixed  for  the  opening,  without  prejudice  to  himself,  by  communicating  his  purpose 
in  writing  to  the  officer  who  holds  it.  No  bids  received  after  the  time  set  for  opening 
the  proposals  will  be  considered. 

3.  Certified  check. — Each  bidder  must  submit  with  his  proposal  a  certified 
check  for  the  sum  stated  in  the  advertisement,  drawn  to  the  order  of  the  Secretary 
of  the  Interior;    and  if,  for  any  reason  whatever,  the  bidder  withdraws  from  the 
competition  after  the  opening  of  the  bids  or  refuses  to  execute  the  contract  and  bond 
as  required,  if  his  bid  is  accepted,  the  proceeds  of  said  check  shall  become  the  prop- 
erty of  the  United  States.     Checks  submitted  by  the  unsuccessful  bidders  will  be 
returned  after  the  approval  of  the  contract  and  bond  executed  by  the  successful 
bidder. 

4.  Eight-hour  law  and  foreign  labor. — In  all  construction  work  eight  hours  shall 
constitute  a  day's  work,  and  no  Mongolian  labor  shall  be  employed  thereon.     The 
importation  of  foreigners  and  laborers  under  contract  to  perform  labor  in  the  United 
States  or  the  Territories  or  the  District  of  Columbia  is  prohibited.     (Section  3738, 
Rev.  Stat.,  U.  S.;  act  Aug.  i,  1892,  27  Stat.  L.,  340;  section  4,  act  June  17,  1902, 
32  Stat.  L.,  388;  acts  Feb.  26,  1885,  and  Feb.  23,  1887,  23  Stat  L.,  332  and  414.) 

5.  Award. — The  bidder  to  whom  award  is  made  will  be  required  to  enter  into 
a  written  contract  with  the  United  States,  with  good  and  approved  security  as  herein 
specified,  within  ten  days  after  receiving  such  contract  for  execution.     The  contract 
which  the  bidder  promises  to  enter  into  shall  be,  in  its  general  provisions,  in  the 
form  adopted  by  the  Reclamation  Service,  copies  of  which  can  be  inspected  at  its 
offices  and  will  be  furnished,  if  desired,  to  parties  proposing  to  bid.     If  the  bidder 
to  whom  the  first  award  is  made  should  fail  to  enter  into  a  contract  as  herein  pro- 
vided, then  the  award  may  be  annulled  and  the  contract  let  to  the  next  most  desirable 
bidder  in  the  opinion  of  the  Secretary  of  the  Interior;    and  such  bidder  shall  be 
required  to  fulfill  every  stipulation  embraced  herein  as  if  he  were  the  original  party 
to  whom  the  award  was  made.     A  copy  of  the  advertisement  and  of  the  general 
conditions  and  detail  specifications  will  be  attached  to  and  form  part  of  the  contract. 
A  corporation  to  which  a  contract  is  awarded  will  be  required,  before  the  contract 
is  finally  executed,  to  furnish  certificate  as  to  its  corporate  existence,  with  evidence 
to  show  that  the  officer  signing  the  contract  is  duly  authorized  to  do  so  on  behalf  of 
the  corporation. 

6.  Contractor's  bond. — The  contractor  will  be  required  to  give  a  bond  in  the 
sum  of  20  per  cent,  of  the  amount  of  the  contract,  unless  a  different  amount  is 
specified  in  the  advertisement  or  proposal,  conditioned  upon  the  faithful  performance 
by  the  contractor  of  all  the  covenants,  stipulations,  and  agreements  in  the  contract. 
If  at  any  time  during  the  continuance  of  the  contract  the  sureties,  or  any  of  them, 
shall  die,  or  become  irresponsible  in  the  opinion  of  the  Secretary  of  the  Interior,  he 
shall  have  the  right  to  acquire  additional  and  sufficient  sureties,  which  the  con- 
tractor shall  furnish  to  the  satisfaction  of  that  officer  within  ten  days  after  notice, 
and  in  default  thereof  the  contract  may  be  annulled  by  the  Secretary  of  the  Interior 
and  the  work  carried  to  completion  in  the  manner  provided  in  the  contract. 

7.  Transfers. — Transfers  of  a  contract,  or  of  any  interest  therein,  is  prohibited 
by  law. 

8.  Engineer. — Where  the  word  "engineer"  is  used  in  the  general  conditions  01 


SPECIFICATIONS,    RECLAMATION    SERVICE  575 

detail  specifications,  or  in  the  contract,  it  shall  be  and  is  mutually  understood  to 
refer  to  the  chief  engineer  of  the  Reclamation  Service,  or  any  of  his  authorized 
assistants  or  inspectors,  limited  by  the  particular  duties  intrusted  to  them.  The 
engineer  wil  give  the  locations  and  the  grades  for  the  work,  and  no  work  depending 
on  such  locations  and  grades  will  be  commenced  until  these  have  been  established. 
It  shall  be  his  duty  to  point  out  to  the  contractor  any  neglect  or  disregard  of  the 
plans,  specifications,  and  general  conditions  of  the  contract.  Upon  all  questions 
concerning  the  execution  of  the  work  and  the  classification  of  the  material,  in  accord- 
ance with  the  specifications,  the  decision  of  the  engineer  shall  be  binding  on  both 
parties.  All  materials  furnished  and  all  work  done  shall  be  subject  to  rigid  inspec- 
tion, and  if  not  in  accordance  with  the  specifications,  in  the  opinion  of  the  engineer, 
shall  be  made  to  conform  thereto.  Unsatisfactory  material  will  be  rejected  and 
shall  be  immediately  removed  from  the  premises,  at  the  cost  of  the  contractor,  if  so 
ordered  by  the  engineer. 

9.  Contractor. — Whenever  the  word  "contractor"  is  used,  it  shall  be  held  to 
mean  the  party,  firm,  or  corporation  with  whom  the  contract  is  made  by  the  United 
States  for  the  construction  of  the  work,  the  agent  of  this  party  who  may  be  appointed 
to  represent  him  in  the  execution  of  the  work,  or  the  legal  representatives  of  the 
contractor.     The  foreman  in  charge  of  the  work  will  be  held  to  represent  the  con- 
tractor during  the  absence  of  the  latter  or  his  designated  agent. 

10.  Foreman  and  copy  of  plans,  etc. — The  contractor  shall  at  all  times  keep 
upon  the  work  a  copy  of  the  plans  and  specifications,  so  that  reference  may  be  made 
thereto  by  the  engineer,  in  case  of  misunderstanding  or  misconstruction.     In- 
structions given  to  the  contractor's  foreman  or  agent  on  the  work,  by  the  engineer, 
shall  be  considered  as  having  been  given  to  the  contractor  himself. 

11.  Railroad  rates. — Special   concessions  of  rates  have   been  obtained   from 
certain  railroad  companies  foe  the  benefit  of  the  United  States,  which  are  applicable 
in  favor  of  contractors  on  this  work.     Full  information  concerning  the  same  can 
be  obtained  from  the  engineer  in  charge  of  the  project.     Bidders  should  make 
allowance  for  these  concessions. 

12.  Local  conditions. — Bidders  must  satisfy  themselves  as  to  the  nature  of  the 
material  and  as  to  all  local  conditions  affecting  the  work,  and  no  information  derived 
from  the  maps,  plans,  specifications,  profiles,  or  drawings,  or  from  the  engineer 
or  his  assistants,  will  in  any  way  relieve  the  contractor  from  any  risks  or  from  ful- 
filling all  the  terms  of  his  contract. 

13.  Damages. — The  contractor  will  be  held  responsible  for  and,  when  possible, 
be  required  to  make  good,  at  his  own  expense,  any  and  all  damages,  of  whatsoever 
nature,  to  persons  or  property  caused  by  carelessness,  neglect,  or  want  of  due  pre- 
caution on  the  part  of  the  contractor,  his  agents,  employees,  or  workmen.     He 
will  not  allow  any  of  his  agents,  employees,  or  workmen  to  trespass  upon  the  premises 
or  lands  of  persons  in  the  vicinity  of  the  works,  and  will  discharge,  at  the  request 
of  the  engineer,  anyone  in  his  employ  who  may  be  guilty  of  committing  such  damage. 

14.  Drawings  and  specification  requirements. — Any  drawings  or  plans  which 
may  be  listed  in  the  detail  specifications  shall,  together  with  such  detail  specifications, 
be  regarded  as  forming  part  hereof  and  of  the  contract.     The  engineer  will  furnish 
from  time  to  time  such  detail  drawings,  plans,  profiles,  and  special  specifications 
as  may  be  necessary  to  enable  the  contractor  to  complete  the  work  in  a  satisfactory 
manner.     The  general  conditions  and  detail  specifications  shall  apply  to  all  work 


576  RECLAMATION    SERVICE 

done  or  material  furnished,  and  shall  control  the  special  specifications,  where  the 
latter  are  silent.  In  case  of  conflict  in  the  general  conditions,  the  detail  specifica- 
tions, and  the  special  specifications,  the  last  shall  control  in  the  particular  work 
to  which  they  apply. 

15.  Experience. — Bidders  must,  if  required,  present  satisfactory  evidence  that 
they  have  been  regularly  engaged  in  the  business  of  constructing  such  work  as  they 
propose  to  execute,  and  that  they  are  fully  prepared  with  the  necessary  capital, 
machinery,  and  material  to  begin  the  work  promptly  and  to  conduct  it  to  the  satis- 
faction of  the  Department. 

1 6.  Character  of  workmen. — The  contractor  shall  discharge  from  his  service, 
when  required  by  the  engineer,  any  disorderly,  dangerous,  insubordinate,  or  incom- 
petent person  employed  on  or  in  the  vicinity  of  the  works  under  construction  by  the 
United  States.     None  but  skilled  foremen  or  workmen  shall  be  employed  on  work 
requiring  special  qualifications,  as  tunnels,  concrete  work,  etc. 

17.  Methods  and  appliances. — The  methods  and  appliances  adopted  by  the 
contractor  must  be  such  as  will  secure  a  satisfactory  quality  of  work  and  will  enable 
him  to  complete  the  work  in  the  time  agreed  upon.     If  at  any  time  such  methods 
and  appliances  appear  inadequate,  the  engineer  may  order  the  contractor  to  improve 
their  character,  or  increase  their  efficiency,  and  the  contractor  must  conform  to  such 
order;    but  the  failure  of  the  engineer  to  order  such  improvement  of  methods  or 
increase  of  efficiency  will  not  relieve  the  contractor  from  his  obligations  to  perform 
good  work  or  finish  it  in  the  time  agreed  upon. 

1 8.  Material  and  workmanship. — All  materials  must  be  of  the  specified  quality 
and  fully  equal  to  approved  samples,  when  samples  are  required.     All  work  must 
be  done  in  a  thorough  workmanlike  manner  by  mechanics  skilled  in  their  various 
trades,   notwithstanding  any  omission  from  the  drawings  or  specifications;    and 
anything  mentioned  in  the  specifications  and  not  shown  in  the  drawings,  or  shown 
in  the  drawings  and  not  mentioned  in  the  specifications,  must  be  done  as  though 
shown  or  mentioned  in  both. 

19.  Samples. — The  contractor  shall  submit  samples  of  any  or  all  materials  pro- 
posed to  be  used  in  the  work  if  required  to  do  so  by  the  engineer. 

20.  Delays. — The  contractor  shall  not  be  entitled  to  any  compensation  for  delays 
or  hindrances  to  the  work  from  any  cause  whatever.     Extension  of  time  will  be 
allowed  for  unavoidable  delays,  such  as  may  result  from  causes  which,  in  the  opinion 
of  the  engineer,  approved  by  the  Secretary  of  the  Interior,  are  undoubtedly  beyond 
the  control  of  the  contractor,  such  as  acts  of  Providence,  fortuitous  events,  or  the 
like.     If  any  delay  or  hindrance  is  caused  by  specific  instructions  on  the  part  of  the 
Secretary  of  the  Interior  or  the  engineer,  or  by  their  failure  to  provide  material 
sufficient  to  carry  on  the  work,  or  to  give  such  instructions  as  may  be  necessary  for 
the  same,  or  to  provide  necessary  right  of  way,  then  such  delay  will  entitle  the  con- 
tractor to  an  extension  of  time  equivalent  to  the  time  lost  by  such  delay.     The 
engineer  must  receive  from  the  contractor  a  written  notice  of  claim  for  such  delay 
before  any  extension  of  time  will  be  allowed.     Any  extension  of  time,  however,  shall 
not  release  the  sureties  from  their  obligation,  which  shall  remain  in  full  force  and 
effect  until  the  discharge  of  contract.     In  case  the  contractor  should  fail  to  complete 
the  work  in  the  time  agreed  upon  in  the  contract,  or  in  such  extra  time  as  may  have 
been  allowed  for  delays  as  herein  provided,  the  engineer  shall  compute  and  appraise 
the  direct  damages  for  the  loss  sustained  by  the  United  States  on  account  of  further 


SPECIFICATIONS,    RECLAMATION    SERVICE  577 

employment  of  engineers,  inspectors,  and  other  employees,  including  all  disburse- 
ments on  the  engineering  account,  properly  chargeable  to  the  work  as  liquidated 
damages.  The  amount  so  appraised  and  computed  shall  be  deducted  from  any 
money  due  the  contractor  under  his  contract.  The  decision  of  the  chief  engineer 
as  to  the  appraisal  of  such  damages  shall  be  final  and  binding  on  both  parties.  Any 
provisions  in  the  detail  specifications  concerning  deduction  for  delay  shall  be  held 
as  modifying  or  revoking  the  provisions  herein. 

21.  Suspension  oj  contract. — Should  the  contractor  fail  to  begin  the  work  within 
the  time  required,  or  fail  to  begin  the  delivery  of  material  as  provided  in  the  contract, 
or  fail  to  prosecute  the  work  or  delivery  in  such  manner  as  to  insure  a  full  compliance 
with  the  contract  within  the  time  limit,  or  should  any  question  arise  as  to  whether 
or  not  the  contractor  is  properly  carrying  out  the  provisions  of  his  contract  in  their 
true  intent  and  meaning,  at  any  time  during  the  progress  of  the  work,  notice  thereof 
in  writing  shall  be  served  upon  him,  and  upon  his  neglect  or  refusal  to  provide 
means  for  a  more  energetic  and  satisfactory  compliance  with  the  contract  within  the 
time  specified  in  such  notice,  then  and  in  either  case  the  Secretary  of  the  Interior 
shall  have  the  power  to  suspend  the  operation  of  the  contract,  and  he  may  take 
possession  of  all  machinery,  tools,  appliances,  and  animals  employed  on  any  of  the 
works  to  be  constructed  under  the  contract  and  of  all  materials  belonging  to  the 
contractor  delivered  on  the  ground,  and  may  use  the  same  to  complete  the  work, 
or  he  may  employ  other  parties  to  carry  the  contract  to  completion,  substitute  other 
machinery  or  materials,  purchase  the  material  contracted  for  in  such  manner  as  he 
may  deem  proper,  or  hire  such  force  and  buy  such  machinery,  tools,  appliances, 
materials,  and  animals  at  the  contractor's  expense  as  may  be  necessary  for  the  proper 
conduct  of  the  work  and,  for  finishing  it  in  the  time  agreed  upon.     Any  excess  of  cost 
arising  therefrom  over  and  above  the  contract  price  will  be  charged  against  the 
contractor  and  his  sureties,  who  shall  be  liable  therefor.     The  failure  to  order 
improvement  of  methods  or  increase  of  force,  plant,  or  efficiencies  will  not  relieve 
the  contractor  from  his  obligation  to  perform  good  work  or  finish  in  the  time  agreed 
upon. 

22.  Climatic  conditions. — The  engineer  may  order  the  contractor  to  suspend 
any  work  that  may  be  damaged  by  inclemency  of  the  weather  or  other  climatic 
conditions  (as,  for  example,  excessive  cold  or  heat)  and  due  allowance  shall  be  made 
to  the  contractor  for  the  time  actually  lost  by  him  on  account  of  such  suspension. 

23.  Quantities. — The  quantities  given  in  the  proposal  are  for  the  purpose  of 
comparing  bids,  and  are  approximate  only,  and  no  claim  shall  be  made   against  the 
United  States  on  account  of  any  excess  or  deficiency,  absolute  or  relative,  in  the 
same. 

24.  Changes. — The  Secretary  of  the  Interior  reserves  the  right  to  make  such 
changes  in  the  specifications  of  work  or  material  at  any  time  as  may  be  deemed 
advisable,  without  notice  to  the  surety  or  sureties  on  the  bond  given  to  secure  com- 
pliance with  the  contract,  by  adding  thereto  or  deducting  therefrom,  at  the  unit 
prices  of  the  contract,  or  at  such  allowances  for  changes  of  materials  as  shall  be 
deemed  just  and  reasonable  by  the  engineer,  whose  decision  shall  be  binding  on  both 
parties.     The  right  to  make  material  changes  in  the  quantities  listed  in  the  proposal 
is  an  essential  part  of  the  contract,  and  bidders  must  make  their  estimates  accord- 
ingly.    Should  any  change  be  made  in  a  particular  piece  of  work  after  it  has  been 
commenced,  so  that  the  contractor  is  put  to  extra  expense,  the  engineer  shall  mako 

37 


578  RECLAMATION    SERVICE 

reasonable  allowance  therefor,  which  action  shall  be  binding  on  both  parties. 
Claim  of  payment  for  extra  work  or  for  work  not  provided  for  in  the  specifications 
will  not  be  allowed  unless  such  work  shall  have  been  previously  ordered  in  writing 
by  the  engineer.  Demand  for  such  extra  payment  must  be  accompanied  by  the 
certificate  of  the  engineer  that  such  work  has  been  satisfactorily  performed  or  the 
material  furnished,  and  stating  the  amount  to  be  allowed  therefor,  which  amount, 
when  no  price  for  work  of  such  kind  is  specified  in  the  proposal,  shall  be  the  reason- 
able actual  cost  to  the  contractor,  plus  15  per  cent.  Such  demand  must  be  made 
before  the  time  of  the  payment  following  the  completion  of  said  extra  work,  or  the 
furnishing  of  the  material. 

25.  Structural  difficulties. — Should  structural  difficulties  prevent  the  execution 
of  the  work  as  described  in  the  plans  and  specifications,  necessary  deviations  there- 
from may  be  permitted  by  the  engineer,  but  must  be  without  additional  cost  to  the 
United  States. 

26.  Inspection  of  work. — The  engineers  and  inspectors  appointed  by  the  Secre- 
tary of  the  Interior  shall  at  all  times  have  the  right  to  inspect  the  work  and  materials. 
The  contractor  shall  furnish  such  persons  reasonable  facilities  for  obtaining  such 
information  as  they  desire  respecting  the  progress  and  manner  of  the  work  and  the 
character  of  the  material,  including  all  information  necessary  to  determine  the  cost 
of  the  work,  such  as  the  number  of  men  employed,  their  pay,  the  time  during  which 
they  worked  on  the  various  classes  of  construction,  etc.-    He  shall,  when  required, 
furnish  the  engineer  and  his  assistants  meals  and  camp  accommodations  at  reason- 
able prices  at  any  camp  under  his  control.     Whenever  the  contractor  shall  decide 
to  inaugurate  night  work,  or  to  otherwise  vary  the  period  during  which  work  is 
carried  on   each   day,   he  shall  give  due  notice  to  the  engineer  so    that    proper 
inspection  may  be  provided  for.     Such  work  shall  be  done    under  regulations 
to  be  furnished  in  writing  by  the  engineer,  and  no  extra  compensation  shall  be 
allowed  therefor. 

27.  Removal  of  defective  work. — The  contractor  shall  remove  and  rebuild,  at  his 
own  expense,  any  part  of  the  work  which  has  been  improperly  executed,  even 
though  such  work  should  have  been  already  allowed  for  in  the  monthly  estimates. 
The  engineer  shall  give  to  the  contractor  written  notice  of  such  defective  work, when 
found.     If  the  contractor  refuses  or  neglects  to  replace  such  defective  work,  it  may 
be  replaced  by  the  United  States  at  the  contractor's  expense. 

28.  Protection  of  finished  work  and  cleaning  up. — The  contractor  will  be  held 
responsible  for  any  material  furnished  to  him,  and  for  the  care  of  any  finished  work 
until  final  completion  of  the  work,  and  will  be  required  to  make  good,  at  his  own 
cost,  any  damage  or  injury  it  may  sustain  from  any  cause.     He  shall  take  all  risks 
from  floods  and  casualties  of  every  description  and  make  no  charge  for  detention 
from  such  causes.     He  may,  however,  be  allowed  a  reasonable  extension  of  time  on 
account  of  such  detention,  as  provided  herein.     The  contractor  shall  remove  all 
rubbish  and  unused  material  upon  completion  of  the  work,  and  place  the  premises 
in  a  condition  satisfactory  to  the  engineer. 

29.  Errors  and  omissions. — The  contractor  will  not  be  allowed  to  take  advantage 
of  any  error  or  omission  in  these  specifications,  as  full  instructions  will  always  be 
given  should  such  error  or  omission  be  discovered. 

30.  Roads  and  fences. — All  roads  crossing  the  work,  and  subject  to  interference 
therefrom,  must  be  kept  open  until  proper  bridges  or  crossings  are  provided  if 


SPECIFICATIONS,    RECLAMATION    SERVICE  579 

necessary,  and  all  fences  crossing  the  work  must  be  kept  up  by  the  contractor  until 
the  work  is  finished. 

31.  Bench-marks,  stakes,  etc. — All  bench-marks  and  side-slope  stakes  must  be 
carefully  preserved  by  the  contractor,  and  in  case  of  their  willful  or  careless  destruc- 
tion or  removal  by  him  or  any  of  his  employees  such  stakes  shall  be  replaced  by  the 
engineer  at  the  contractor's  expense. 

32.  Right  oj  way. — The  right  of  way  for  the  works  to  be  constructed  and  for  all 
necessary  borrow-pits,  spoil-banks,  ditches,  roads,  etc.,  will  be  provided  by  the 
United  States. 

33.  Sanitation. — The  chief  engineer  may  establish  rules  for  sanitary  and  police 
regulations  for  all  forces  employed  under  this  contract;   and  should  the  contractor 
fail  to  enforce  these  rules,  the  engineer  may  enforce  them  and  assess  against  the 
contractor  the  cost  thereof,  which  will  be  deducted  from  any  sum  due  on  the  contract. 

34.  Use  of  liquor. — The  use  and  sale  of  intoxicating  liquor  will  be  absolutely 
prohibited  on  the  work  except  under  the  direction  and  supervision  of  the  engineer 
or  his  agent,  and  then  only  for  medicinal  purposes. 

35.  Claims  for  work  and  material. — The  contractor  shall  promptly  make  pay- 
ments to  all  persons  supplying  labor  and  materials  in  the  prosecution  of  the  work, 
and  a  condition  to  this  effect  shall  be  incorporated  in  the  bond  to  be  given  by  the 
contractor,  in  pursuance  of  the  act  of  Congress  approved  August  13,  1894  (28Stat., 
278). 

36.  Payments. — The  payments  due  shall  be  made  to  the  contractor  upon  the 
presentation  of  proper  accounts,  prepared  by  the  engineer  and  approved  by  the 
chief  engineer,  in  accordance  with  the  provisions  made  therefor  and  pertaining  to  the 
contract.     When  the  work  has  been  completed  or  all  the  material  has  been  delivered, 
to  the  satisfaction  of  the  chief  engineer,  and  when  a  release  of  all  claims  against  the 
United  States  on  account  of  the  contract  shall  have  been  executed  by  the  contractor, 
final  payment  of  the  balance  due  will  be  made. 

DETAIL  SPECIFICATIONS. 

37.  Object  oj  the  work. — The  object  of  the  work  is  the  construction  of  a  masonry 
dam  in  the  canyon  of  the  Salt  River  below  the  mouth  of  Tonto  Creek,  Ariz.,  for  the 
purpose  of  impounding  about  1,000,000  acre-feet  of  water.     Two  spillways,  each 
about  200  feet  long,  carry  the  flood  waters  around  the  dam.     A  roadway  is  carried 
across  the  dam,  crossing  the  spillways  on  concrete-steel  bridges.     The  general 
dimensions  of  the  dam  are  as  follows: 

FRET. 

Height  of  spillway  above  datum  or  mean  low  water 210 

Height  of  roadway  above  datum  or  mean  low  water 230 

Lowest  point  of  foundation  below  datum 36 

Length  of  dam  at  datum 210 

Length  of  dam  at  spillway 780 

38.  List  of  drawings. 

No.  i.  Plan  of  east  half  of  dam,  abutment,  and  spillway. 
No.  2.  Plan  of  west  half  of  dam,  abutment,  and  spilhvay. 
No.  3.  Cross-section  of  dam. 
No.  4.  Plan,  cross-sections,  and  elevation  of  bridges  and  piers. 


580  RECLAMATION    SERVICE 

39.  Diversion. — Floods  exceeding  4,000  second-feet  are  liable  to  go  over  the 
dam.     The  river,  at  low  stage,  shall  be  diverted  through  the  tunnel  or  temporary 
flume  by  means  of  a  temporary  diversion  dam  not  less  than  12  feet  high  above  the 
bottom  of  the  tunnel,  and  made  as  tighUas  practicable  with  sheet-piling  securely 
connected  with  the  dam.     The  stream  shall  be  conducted  well  below  the  vicinity 
of  the  dam  before  discharging  into  the  river.     A  row  of  sheet-piling  shall  also  be 
driven  across  the  canyon  below  the  dam  site  to  prevent  the   return  of  water  by 
seepage.     As  soon  as  practicable  a  tight  wooden  flume,  not  less  than  50  feet  wide 
afnd  5  feet  deep,  shall  be  provided,  leading  from  a  level  5  feet  below  the  top  of  the 
diversion  dam  and  discharging  below  outlet  of  tunnel.     The  construction  of  dams, 
cofferdams,  flumes,  and  all  other  diversion  and  protection  works  shall  be  done  at  the 
contractor's  cost  without  extra  compensation.     The  necessary  lumber  for  such 
works  will  be  furnished,  after  due  notice,  by  the  United  States  at  the  dam  site  at 
the  rate  of  $25  per  M  feet,  board  measure,  the  charge  therefor  to  be  deducted  in  the 
monthly  statements  of  amounts  due  the  contractor.     No  sawed  lumber  over  22  feet 
in  length  can  be  furnished. 

40.  Excavation. — All  material  will  be  measured   in   place,   and  the  material 
excavated  from  the  foundation  shall  be  paid  for  in  three  classes,  viz. : 

Class  i.  Loose  material  consisting  of  sand,  gravel,  and  bowlders  of  less  than 
10  cubic  feet,  and  all  other  material  which  may  occur  excepting  solid  rock  in  place. 

Class  2.  Solid  rock  in  place,  lying  below  the  datum,  which  is  about  low-water 
surface,  and  bowlders  of  10  cubic  feet  or  larger. 

Class  3.     Solid  rock  in  place  above  the  datum. 

41.  Foundation. — The  foundation  shall  be  thoroughly  cleaned  of  all  gravel, 
sand,  and  earth,  and  all  fissured  or  disintegrated  rock  shall  be  removed  so  that  the 
dam  shall  be  founded  on  solid  rock  throughout,  and  in  such  manner  as  required  by 
the  engineer  in  charge.     Explosives  shall  not  be  used  in  excavating  the  rock  in  the 
foundation  unless  absolutely  necessary;  and  when  used,  shall  be  in  small  quantities 
only,  and  in  a  manner  approved  by  the  engineer.     A  trench  shall  be  cut  in  the  solid 
rock  of  the  foundation  15  feet  from  the  heel  of  the  dam,  and  parallel  thereto,  and 
shall  be  10  feet  wide  and  6  feet  deep  below  the  bottom  of  the  dam  on  the  line  of  the 
trench. 

42.  Removal  of  temporary  works. — All  cofferdams  or  other  temporary  works 
shall  be  removed  by  the  contractor,  free  of  cost,  at  such  times  as  the  engineer  may 
direct. 

43.  Side  walls. — Above  the  bed  of  the  river  the  side  walls  shal  be  cut  away  until 
they  present  surfaces  normal  to  the  face  of  the  dam  suitable,  in  the  judgment  of  the 
engineer,  for  solid  and  safe  junction  with  the  masonry.     This  shall  be  paid  for  by 
the  cubic  yard  as  solid  rock  at  the  price  agreed  upon  in  the  contract;   any  earth  or 
loose  material  occurring  in  the  side  walls  will  be  small  in  amount  and  shall  be  re- 
moved by  the  contractor  without  extra  charge. 

44.  Overhaul. — All  material  excavated  from  the  foundations  and  side  walls 
shall  be  placed  where  directed  by  the  engineer.     Whenever  the  engineer  may  require 
any  material  transported  more  than  300  feet  from  the  point  of  excavation  the 
distance  over  300  feet  will  be  paid  for  as  overhaul  at  the  price  agreed  upon  in  the 
contract. 

45.  Masonry. — The  main  body  of  the  dam  shall  be  constructed  of  broken  range 
cyclopean  rubble,  laid  so  as  to  break  joints  and  thoroughly  bond  the  work  in  all 


SPECIFICATIONS,    RECLAMATION    SERVICE  581 

directions.  The  stone  shall  be  quarried  from  the  walls  on  each  side  of  the  canyon 
shown  in  the  drawing  as  proposed  spillways.  If  a  sufficient  quantity  of  hard  fine- 
grained stone  can  not  be  obtained  in  these  spillways  it  shall  be  quarried  from  the 
bluffs  at  either  end  of  the  dam  at  locations  designated  by  the  engineer,  at  the  con- 
tractor's expense.  Each  stone  shall  be  thoroughly  drenched  and  cleaned  of  dirt 
and  laid  in  Portland  cement  mortar  of  the  quality  hereafter  specified.  Vertical 
joints  between  the  stonts  inside  of  the  face  stone  of  the  dam  must  be  nowhere  less 
than  6  inches,  and  must  be  thoroughly  filled  with  Portland  cement  concrete,  or 
mortar,  which  should  be  rammed  into  place  by  hand,  to  the  end  that  all  space  in  the 
dam  not  occupied  by  stone  shall  be  absolutely  filled  with  mortar.  Spalls  may  be 
rammed  into  the  mortar  in  the  vertical  joints  and  rock  may  be  rammed  into  the 
concrete  where  the  joints  are  large  enough.  No  rock  shall  come  nearer  to  another 
than  2  inches.  All  overhanging  edges  shall  be  hammered  off,  and  concave  or 
otherwise  improper  beds  are  prohibited.  The  aim  shall  be  to  use  the  largest  pro- 
portion of  stone  and  the  smallest  proportion  of  mortar  and  concrete  in  the  dam  that 
can  be  practically  secured.  To  this  end  facilities  shall  l>e  provided  for  handling 
stones  weighing  10  tons,  and  large  stones  shall  be  used  as  far  as  practicable. 

46.  Water-pipes. — The  contractor  shall  provide  water-pipes  on  the  work,   by 
which  at  any  time  any  portion  of  the  masonry  may  be  thoroughly  wet,  and  these 
shall  be  used  whenever  required  by  the  engineer.     All  masonry  shall  be  kept  wet 
during  the  time  of  construction  and  until  the  work  is  at  least  six  days  old. 

47.  Up-stream  /ace. — The  stone  for  the  up-stream  face  shall  be  selected  so  as 
to  lie  with  horizontal  beds  and  vertical  joints  in  Portland-cement  mortar,  composed 
of  i  part  cement  to  2  parts  sand.     No  mortar  joint  in  the  face  shall  exceed  2  inches 
in  thickness.     At  least  one-third  of  the  area  in  the  face  must  be  headers  evenly 
distributed  throughout  the  wall,  and  every  header  shall  be  laid  over  a  stretcher  of 
the  underlying  course.     The  stone  shall  be  so  arranged  as  to  break  joint  in  no  case 
less  than  i  foot  with  the  stone  of  the  underlying  course.     The  stretchers  must  be  not 
less  than  3  feet  long  nor  less  than  2  feet  in  any  other  dimension;   the  headers  must 
not  be  less  than  6  feet  in  length  nor  less  than  2  feet  in  any  other  dimension.     The 
joints  in  tlr's  face  of  the  dam  shall  be  dug  out  to  a  depth  of  at  least  3  inches  and  at 
such  times  as  directed  shall  be  carefully  pointed  by  hand  with  mortar  composed  of 
equal  parts  of  sand  and  cement,  or  with  such  material  as  shall  be  required  by  the 
engineer  and  furnished  by  the  United  States,  and  this  shall  be  done  as  thoroughly 
as  possible  in  order  to  make  a  water-tight  surface.     Immediately  before  pointing, 
the  joints  shall  be  thoroughly  washed  out  with  a  hose.     Projections  of  12  inches  or 
less  beyond  the  lines  of  the  drawings,  will  be  permitted  where  they  are  of  such 
symmetry  as  not  to  be  unsightly.     The  face  wall  shall  be  kept  at  all  times  at  least 
one  course  higher  than  the  body  of  the  dam  opposite. 

48.  Down-stream  face. — The  stone  for  the  down-stream  face  shall  be  so  selected 
as  to  lie  with  horizontal  beds  and  vertical  joints,  and  each  stone  shall  be  laid  in  a  bed 
of  cement  mortar  composed  of  sand  and  cement  in  the  proportion  directed  by  the 
engineer;   where  not  otherwise  directed  the  proportions  shall  be  i  part  of  cement 
to  2\  parts  of  sand.     At  least  one-fourth  of  the  area  in  the  face  must  be  headers 
evenly  distributed  throughout  the  wall,  and  every  header  shall  be  laid  over  a  stretcher 
of  the  underlying  course.     The  stone  shall  be  laid  in  steps  and  shall  have  a  proper 
bond  with  the  stone  of  the  underlying  course.     Projections  of  2  feet  or  less  beyond 
the  lines  of  the  drawing  will  be  permitted  where  they  are  of  such  symmetry  as  not 


582  RECLAMATION    SERVICE 

to  be  unsightly.  Payments  will  be  made  in  every  case  for  material  within  the  neat 
lines  of  the  drawing  only.  The  face  wall  shall  be  kept  at  all  times  at  least  one 
course  higher  than  the  body  of  the  dam  opposite. 

49.  Wing  walls. — Two  rubble-masonry  wing  walls  of  the  same  character  of 
masonry  as  the  body  of  the  dam  shall  be  constructed  as  shown  in  the  drawings. 
The  dimensions  of  these  wing  walls  are  dependent  on  the  character  of  the  rock  and 
can  only  be  accurately  determined  when  the  excavation  is  complete. 

50.  Outlet  pipes. — The  United  States  reserves  the  right  to  require  the  insertion, 
in  such  manner  as  the  engineer  may  direct,  of  large  pipes  for  drawing  water  through 
the  dam.     All  pipes  to  be  built  in  the  dam  will  be  furnished  by  the  United  States 
at  the  dam  site  and  shall  be  built  in  by  the  contractor.     The  price  of  laying  to  be 
included  in  the  price  for  masonry  and  paid  for  by  the  cubic  yard  at  the  same  rate 
as  masonry. 

51.  Coping,  etc. — The  coping,  roadway,  guide  walls,  bridge  piers,  bridges,  gate 
shaft,  and  spillways  shall  be  built  and  finished  in  a  workmanlike  manner  as  shown 
in  the  drawings.    The  contractor  shall  insert,  in  the  position  and  manner  designated 
by  the  engineer,  such  iron  or  steel  as  may  be  required  and  furnished  by  the  United 
States. 

52.  Concrete. — All  concrete  used  in  the  dam  shall  be  composed  of  Portland 
cement,  sand,  and  broken  stone,  in  the  proportion  by  volume  directed  by  the  engi- 
neer.    The  run  of  crusher  will  be  taken,  the  parts  passing  a  |-inch  screen  being 
classed  as  sand.     The  sand  shall  be  free  from  organic  matter,  and  contain  not  more 
than  10  per  cent  of  clay  or  other  foreign  mineral  substance.     Where  not  otherwise 
directed,  the  proportions  of  separate  aggregates  shall  be  i  part  of  cement,  z\  parts 
sand,  and  4  parts  of  broken  stone  of  such  size  as  to  pass  through  a  2-inch-mesh 
screen. 

53.  Sand. — The  contractor  shall  provide  screens  for  ascertaining  the  proportion 
of  materials  of  various  sizes  produced  by  the  crusher,  in  order  to  enable  the  engineer 
to  determine  the  necessary  proportion  of  sand  in  the  concrete;  and  he  shall  at  inter- 
vals, when  required,  make  such  tests  as  may  be  necessary  for  this  purpose  without 
extra  charge.     Sand  required  in  addition  to  the  run  of  the  crusher,  or  such  sub- 
stitute as  the  engineer  may  adopt,  will  be  furnished  by  the  -United  States  at  the  dam 
site,  without  cost  to  the  contractor. 

54.  Mixing. — The  mixing  shall  be  done  by  a  machine  whenever  practicable, 
and  the  style  of  machine  shall  be  subject  to  approval  by  the  engineer.     Whenever 
the  machine  fails  to  perform  the  mixing  thoroughly  it  must  be  made  satisfactory  or 
removed  and  another  machine  substituted.     When  from  any  cause  resort  to  hand- 
mixing  is  necessary,  this  shall  be  done  thoroughly  and  to  the  satisfaction  of  the 
engineer. 

55.  Water. — The  water  used  for  mixing  must  be  free  from  organic  matter.     The 
amount  of  water  used  both  in  mixing  and  seasoning  the  concrete  after  it  it  placed 
in  the  work  must  be  satisfactory  to  the  engineer.     All  concrete  will  be  used  as  wet 
as  will  give  good  results  and  as  the  nature  of  the  work  will  permit. 

56.  Cement. — All  cement  will  be  furnished  by  the  United  States  and  will  be 
delivered  to  the  contractor  near  the  cement  mill  in  Tonto  Basin. 

57.  Time  of  beginning  work. — Within  twenty  days  after  receipt  of  contract  for 
signature  the  successful  bidder  shall  execute  the  same  and  file  a  satisfactory  bond. 
Within  thirty  days  after  notice  of  signature  of  contract  by  the  Secretary  of  the 


SPECIFICATIONS,    RECLAMATION    SERVICE  583 

Interior,  the  contractor  shall  begin  work  under  the  contract,  and  within  ninety  days 
thereafter  shall  have  on  the  work  as  large  a  force  as  can  be  economically  employed, 
and  a  plant  adequate  to  prosecute  the  work  in  the  most  rapid  and  efficient  manner 
practicable  and  carry  it  to  completion  as  specified  in  the  proposal.  He  shall  employ 
three  daily  shifts  of  eight  hours  each  on  masonry  construction,  and  shall  provide  an 
ample  number  of  electric  lights  to  efficiently  illuminate  all  work  in  progress  at  night. 
The  number  of  lamps  and  the  type  thereof  shall  be  subject  to  the  approval  of  the 
engineer. 

58.  Default. — Should  the  contractor  fail  to  begin  the  work  within  the  time 
allowed,  or  fail  to  begin  the  delivery  of  material  as  provided  in  the  contract,  or  fail 
to  prosecute  the  work  or  delivery  in  such  manner  as  to  insure  a  full  compliance  with 
the  contract  within  the  time  limit,  or  default  in  any  other  manner  in  the  proper 
execution  of  the  work,  all  the  machinery,  tools,  appliances,  and  animals  employed 
on  any  of  the  works  to  be  constructed  under  the  contract  and  all  materials  belonging 
to  the  contractor  delivered  on  the  ground  shall  be  and  become  absolutely  the  prop- 
erty of  the  United  States. 

59.  Deduction  /or  failure  to  complete. — Bidders  will  state  in  their  proposals 
the  time  in  which  they  propose  to  complete  the  dam  to  a  height  of  150  feet  above  the 
datum,  which  datum  is  about  low-water  mark.    Time  is  an  element  in  the  construc- 
tion of  this  work  and  will  be  considered  in  the  examination  and  comparison  of  bids 
and  the  award  of  the  contract  therefor.    If  the  work  is  not  completed  within  the  time 
agreed  upon  in  the  contract  there  will  be  deducted  from  all  payments  made  on  said 
work  after  the  expiration  of  said  time  the  sum  of  $250  per  day  for  every  day  occupied 
in  excess  of  the  time  agreed  upon  in  the  contract,  as  liquidated  damages  for  the  loss 
to  the  Government  on  account  of  engineering,  superintendence,  and  the  value  of  the 
operation  of  the  irrigation  works  dependent  thereon,  said  sum  to  be  deducted  from 
any  amount  due  under  the  contract. 

60.  Completion. — After  the  completion  of  the  dam  to  the  i5o-foot  level,  it  shall 
be  discretionary  with  the  engineer  whether  masonry  work  on  the  dam  be  permitted 
during  the  months  of  June,  July,  August,  and  September,  but  work  shall  be  prose- 
cuted vigorously  and  continuously  during  the  remaining  eight  months  of  the  year, 
at  a  rate  per  month  of  not  less  than  two-thirds  of  that  achieved  during  the  construc- 
tion of  the  lower  portion  of  the  dam,  considered  in  cubic  yards  of  masonry  laid.    The 
contractor  shall  place  in  the  masonry  such  iron  and  steel  in  such  manner  as  the  en- 
gineer may  direct.    The  metal  will  be  furnished  at  the  dam  site  by  the  United  States. 
The  United  States  reserves  the  right  to  vary  the  section  of  the  dam  above  the  150- 
foot  level.    The  section  shown  on  drawings  is  for  comparison  of  bids  only. 

61.  Power  plant. — The  United  States  reserves  the  right  to  construct  a   power 
plant  at  or  near  the  location  shown  in  the  drawings  without  hindrance  from  the  con- 
tractor.   The  power  house  may  be  built  by  the  same  contractor  as  the  one  building 
the  dam,  by  another  contractor,  or  by  the  United  States,  as  may  best  conserve  the 
public  interests.    After  the  work  on  the  power  plant  is  begun,  that  portion  of  the 
dam  adjacent  to  the  left  bank  must  be  kept  at  least  10  feet  higher  than  the  rest  of  the 
dam,  as  a  protection  to  the  power  house  in  case  of  overflow.     The  United  States 
reserves  the  right  to  store  and  use  the  water  in  the  reservoir  up  to  a  level  25  feet  below 
the  lowest  point  of  the  top  of  the  masonry. 

62.  Power. — Electric  energy  for  all  lights  for  construction  purposes  will  be 
furnished  free  of  charge  at  the  darn.    Electric  energy  for  all  power  purposes  required 


584  RECLAMATION    SERVICE 

by  the  contractor  will  be  furnished  at  the  dam,  to  be  measured  at  the  power  plant  and 
charged  for  at  the  rate  of  £  cent  per  horse-power  hour  up  to  a  limit  o/  400  horse- 
power, and  i  cent  per  horse-power  hour  for  all  power  in  excess  of  400  horse-power  the 
charges  therefor  to  be  deducted  in  the  monthly  statements  of  amounts  due  the  contrac- 
tor. The  United  States  does  not  guarantee  the  delivery  of  more  than  600  horse-power. 

63.  Repairs. — Repairs   required   by   the   contractor   will   be   performed   when 
feasible  in  the  repair  shop  attached  to  the  cement  mill,  and  will  be  charged  at  cost 
for  necessary  labor  and  material  plus  15  per  cent  for  use  of  tools. 

64.  Payment  of  employees. — The  contractor  shall  make  such  banking  arrange- 
ments that  his  employees  may  not  be  subjected  to  loss  in  securing  their  wages. 

65.  Payments  to  contractor. — Payments  will  be  made  to  the  contractor  as  follows: 
At  the  end  of  each  calendar  month  the  engineer  shall  make  an  approximate  measure- 
ment of  all  the  work  done  up  to  that  date,  and  an  estimate  of  the  value  of  the  same 
at  the  prices  agreed  upon  in  the  contract.    A  deduction  of  20  per  cent  shall  be  made 
from  this  estimated  amount,  and  from  the  balance  shall  be  deducted  the  amount  of  all 
previous  payments.    The  remainder  shall  be  paid  to  the  contractor  upon  the  presen- 
tation of  proper  accounts.     The  20  per  cent  so  deducted  shall  be  retained  by  the 
Government  until  the  work  shall  have  been  completed  to  the  entire  satisfaction  of  the 
chief  engineer  and  the  Secretary  of  the  Interior,  and  then  be  payable  to  the   con- 
tractor, his  heirs,  assigns,  or  legal  representatives;   provided,  however,  that  in  the 
event  of  default  on  the  part  of  the  contractor  all  of  the  moneys  retained  under  this 
paragraph  in  the  hands  of  the  Government  shall  be  and  become  absolutely  the  prop- 
erty of  the  United  States  in  reimbursement  of  any  damage  which  may  result  through 
the  failure  of  the  contractor  to  fully  and  satisfactorily  comply  with  the  terms  and 
conditions  of  his  contract.    After  50  per  cent  of  the  work  shall  have  been  completed 
the  foregoing  deduction  of  20  per  cent  shall  no  longer  be  made,  but  the  contractor 
shall  be  paid  the  full  value  of  the  work  done  during  each  month.    The  balance  due 
upon  completion  of  the  work  shall  be  paid  as  provided  in  paragraph  36. 

422.  Unit  Costs,  Reclamation  Service. — The  following  are 
some  of  the  unit  costs  of  construction,  both  by  contract  and  by 
force  account,  on  Reclamation  Sendee  projects.  These  furnish 
excellent  examples  of  prevailing  prices  in  the  arid  regions  in  1908. 
Comparative  earthwork  costs  in  the  northwest  are  analyzed  by 
chief  engineer  Arthur  P.  Davis  as  follows: 

Cold  Springs  Earth  Dam,  Umatilla  Project,  Oregon. 

COST  OF  PRINCIPAL  EQUIPMENT. 

Items.  Cost.  Depreciation. 

One  steam  shovel,  7o-ton,  z\  yd $14,147  $8,147 

Four  locomotives,  i6-ton    I5>i2i  7>°5i 

Forty-five  dump  cars I2>fi72  9,102 

Four  miles  3o-in.  track,  35~lb.  rails. .  .  .    25,187  20,447 

Trestle 10,263  9*263 

•Sundries 270 

Total $78,590  $54,280 


UNIT    COSTS,    RECLAMATION    SERVICE  585 

The  total  depreciation  on  the  equipment  has  been  figured  at 
$54,280.  The  total  amount  of  gravel  required  is  estimated  at 
590,000  cu.  yd.,  making  the  cost  of  depreciation  of  plant  per  cubic 
yard  moved,  9.2  cents. 


COST    OF    GRAVEL    EMBANKMENT  AND    OF 
EARTH  EMBANKMENT. 

Gravel  Embankment:  C'ents. 

Excavation  by  steam  shovel 3.5 

Hauling,  railroad  maintenance,  etc 7.0 

Spreading  and  mixing 8.8 

Sprinkling i  .o 

Rolling 5 

Engineering,  superintendence  and  general  expense 5.7 

Repairs 5 

Depreciation  of  plant (> .  a 


Total  cost  per  cubic  yard 36.  2 

Earth  Embankment: 

Loading  and  hauling g .  5 

Spreading  and  mixing 3.8 

Sprinkling i  .  i 

Rolling 8 

Depreciation 4.2 

Repairs   3 

Engineering,  superintendence  and  general  expenses 3.7 


Total  cost  per  cubic  yard 23 . 4 

As  the  dam  is  approximately  one-fourth  loam  and  three-fourths 
gravel,  the  combined  cost  is  33  cents  per  cubic  yard,  measured  in 
excavation.  The  thorough  mixing  and  compacting  causes  a 
shrinkage  of  about  16  per  cent.,  making  the  cost  in  embankment 
about  39  cents. 

Contract  bid  on  the  above  Vork  was  38  per  cent,  higher  than 
cost  as  constructed  on  force  account. 


586  RECLAMATION    SERVICE 


COST  OF  UPPER  DEER  FLAT  EMBANKMENT, 
PAYETTE  PROJECT,  IDAHO. 

Per    yard. 

Excavation 6.3 

Hauling 8.3 

Spreading 1.8 

Sprinkling 1.8 

Rolling 1.3 

Depreciation  4.1 

Engineering,  superintendence  and  general  expenses 3.9 


Total  cost  per  cubic  yard 27.5 

Eliminating  the  items  of  engineering  and  general  administra- 
tive expenses,  which  would  have  been  incurred  had  the  work  been 
contracted,  there  would  have  been  a  cost  of  about  26  cents  per 
yard,  as  against  the  lowest  bid  price  of  36  cents. 

COST  OF  EARTHWORK  ON  BELLE  FOURCHE  DAM,   SOUTH 

DAKOTA. 

Steam  shovel  Grader 

Item.                                                      work.  work. 

305,000  cu.  yd.       199,000  cu.  yd. 

Loading $0.067  $0.054 

Hauling .079  .113 

Spreading .101  .015 

Sprinkling .015  .013 

Rolling .012  .015 

Depreciation  and  repairs .091  .034 

Administration .033  .022 


Total  cost  per  cubic  yard $0.398  $0.266 

Aggregate  total  cost $121,338  $52,814 

The  average  daily  output  per  steam  shovel  was  950  cu.  yds., 
at  a  cost  of  $15  per  day  worked. 

Comparing  the  above  with  Eastern  conditions  it  appears  that 
the  difference  in  price  and  quality  of  coal  for  power  production 
adds  2  to  3  cents  per  yard.  There  is  an  average  of  two  working 


UNIT   COSTS,    RECLAMATION    SERVICE 


587 


days  more  per  month  in  the  West  than  the  East,  due  to  less 
rainfall,  allowing  for  which  makes  wages  in  the  West  cost  39 
per  cent,  more  than  in  the  East.  Including  higher  freight,  diffi- 
culty of  making  repairs,  etc.,  this  class  of  work  costs  25  to  50  per 
cent,  more  in  the  West  than  in  the  East,  depending  on  locality 
and  accessibility. 

The  following  are  some  unit  prices  bid  on  contract  work: 


CONCRETE. 

Per   cu.    yd. 

Belle  Fourche,  S.  D.,  dam $6.50  to  $7.00 

Lower  Yellowstone,  Mont.,  canal  structures 4.25  to    6.25 

Minidoka,  Idaho,  dam 5.00  to    6.00 

Salt  River,  Ariz.,  spillway 6.00 

Truckee-Carson,  Nev.,  turnouts,  foundations 10.00  to  12.00 

Umatilla,  Ore.,  dam  and  canal  structures   6.00  to    8.00 

Yuma,  Cal.-Ariz.,  core-wall 4.00 


EARTH  EXCAVATION. 
COST  PER  CUBIC  YARD. 


Loose  Material. 
Plowable  2-4 
Horses 

Heavy.  Plowable 
6-8  Horses. 

Indurated.  Blast- 
ing and  Scrapeis. 

Belle  Fourche,  S.  D. 
Borrow  pits 

to   ic 

Grading  and  embankment 

«*_>.  i^ 
$o   1  6  —       ^o 

$o   2^—  $o  42 

North  Platte,  Wyo. 
Main   canal     .    . 

1  1—          14 

40—        60 

Lateral  canals  

.  18-     .  ii 

•4U 
.  ^5—      .  60 

Truckee-Carson,  Nev. 
Main  canal 

2O  —          2  1 

•ic—         TO 

Lateral  canals      

I  7—       .  I  C 

$O    12—  to.  15 

•25—       .4.C. 

Uncompahgre,  Col. 
Main  canal  

.11—       .14 

.16 

.25-      .28 

Hondo  N  M    dam 

11—        l% 

.46 

Lower  Yellowstone,  Mont. 
Main  canal 

12  —         14 

.  28-      .  14 

Pavette-Boise  Idaho  dam 

•  T> 

.  10-      .  IS 

588 


RECLAMATION    SERVICE 


LOOSE  ROCK  EXCAVATION. 

COST  PER  CUBIC  YARD. 


2    1O    10   CU.    ft. 

10  to  15  cu.  ft. 

15  to  30  cu.  ft. 

Lower  Yellowstone,  Mont., 
canal  

$O  .  3O—  $O     CJO 

Truckee-Carson,  Nev., 
canal  

•JO—            2s 

North  Platte,  Wyo.,  canal  .  .  . 

•  ow         -oo 

$o.  3S—  $o.  7? 

*u-ou      *-3^ 

Payette-Boise,  Idaho,  canal 

e  r—          ?C 

Hondo,  N.  M.,  dam  

•  JJ            '  /O 

Uncompahgre,  Col.,  canal  .  .  . 

?  r 

SOLID  ROCK  EXCAVATION. 
COST  PER  CUBIC  YARD. 

Belle  Fourche,  South  Dakota,  canal   $i .  05 

Klamath,  California,  canal i .  25 

Lower  Yellowstone,  Montana,  main  canal  and  structures 65 

Minidoka,  Idaho,  laterals i .  50 

Canal . $o .  90-     .  95 

North  Platte,  Wyoming,  canal 50-     .  80 

Payette-Boise,  Idaho,  canal i .  15-  i .  25 

Salt  River,  Arizona,  Roosevelt  dam i .  50 

Truckee-Carson,  Nevada,  canal   80 

Uncompahgre,  Colorado,  canal    95 

Yuma,  California- Arizona,  Laguna  dam i .  30 

MISCELLANEOUS. 


Ce- 
ment. 

Gates 
and 
Guides. 

Lum- 
ber. 

Pave- 
ment 
Head- 
works. 

Pud- 
dling. 

Rip- 
rap. 

Rock- 
fill. 

Belle  Fourche  S.  D  

bbl. 

$21* 

pound. 

$o  ex 

1000  ft. 

sq.  yd. 
$2    18 

cu.  yd. 

cu.  yd. 

cu.  yd. 

Payette-Boise  Idaho 

06 

$O    3O 

$1     2S 

Truckee-Carson,  Nev  
Umatilla  Wash. 

2-55 

.07 

•45 

70 

1.50 

$2  .  OO 

300 

$1     ^O 

Yuma,  Cal.-Ariz  
Lower  Yellowstone,  Mont  .  .  . 

2.76 
2    8O 

.... 

I  .00 

sO 

2    OO 

•35 

North  Platte,  Neb  

2    2O 

7c 

Klamath,  Cal  

Minidoka,  Idaho  

2    0? 

oc 

OO 

UNIT    COSTS,    RECLAMATION    SERVICE  589 

Reinforcing  steel  used  in  the  canal  lining  of  Uncompahgrc 
project,  Colorado,  cost  0.034  cent  per  pound,  0.016  cent  per 
linear  foot  of  bars,  and  0.895  cent  Per  cubic  yard  of  concrete. 

Contract  prices  for  pressure  stave  pipes  for  Salt  River  project 
were : 

Pressure  Head  Per  Linear 

in  Feet.  Foot. 

10-20 $5.  13 

20-30 5.53 

30-40 5-94 

40-50.  ...  6.34 

Additional  price  for  each  additional  lo-foot  increment  in 
pressure  up  to  200  feet,  53  cents. 


INDEX 


PAGE 

Absorption 20 

Amount  of,  in  Reservoirs  and  Canals 30 

Works  of  Reference 33 

Acoustic  Current  Meter 71 

Acre  foot 47 

Duty  of  Water  per 53 

Agra  Canal,  Iron  Aqueduct 286 

Kushuk  Fall  on 265 

Scouring  Sluices 211 

Alcohol  Pumping-Engines    541 

Alignment  of  Canals    127 

Canals,  Obstacles  to    131 

Ganges  Canal : 135 

Santa  Ana  Canal    " 143 

Turlock  Canal    138 

Alkali : 34 

Causes  of 34 

Growth  of  Suitable  Plants  in   38 

Leaching  and  Mulching  of 38 

Prevention  of    35 

Soil,  Chemical  Treatment  of    36 

Works  of  Reference   46 

Alkaline  Water,  Use  of 36 

Allen,  C.  A .  r  1 7,  346 

Altitude,  Increase  of  Rainfall  with    g 

American  Society  of  Irrigation  Engineers    31 ; 

Well  Works 487 

Application  of  Sewage,  Methods  of 114 

Water,    Methods  of 321 

Works  of  Reference    352 

Aprons  to  Weirs 183 

Aqueducts  and    Flumes    272 

Interstate  Canal 284 

Iron    276 

Agra  Canal 286 

Bear  River  Canal,  Utah    277 

Henares  Canal,  Spain 278 

Masonry    279 

Nadrai,  over  Kali  Nadi  on  Lower  Ganges  Canal,  India 282 

591 


59  2  INDEX 

PAGE 

Aqueducts  and  Reinforced  Concrete   283 

Solani  River,  Ganges  Canal,  India 136,  279 

Arched  Masonry  Walls 474 

Archimedean  Screw 512,  =u^ 

Areal  Duty  of  Water   54 

Arizona  Canal    254 

Plan  of  Headworks    229 

Regulator  Gates 23^ 

Weir   1 79 

Artesian  Water,  Storage  of 96 

Wells    •. 94 

Capacity  and  Cost  of 95,  507 

Drilling,  Manner  of 97 

Machinery  for t .  .  .  .     98 

Process  of    100 

Examples  of    94 

Sizes  of 96 

Sources  of    93 

Works  of  Reference 117 

Ash  Fork  Dam 474,  478 

Ashlar-Faced  Concrete  Weir    .  . .  ." 194 

Ashti  Dam    372 

Asphalt  Lining  of  Dams 435 

Assiout  Weir 122,  457 

Associations,  Water  Users'   569 

Assuan  Dam   457 

Atmospheric  Pressure    60 

Austin  Dam 462 

Automatic  Drop-shutter    489 

Gates 488 

Shutters 488 

Sluice  Gates   221,  224 

Wasteway  Gate 226 

Weir  Gates 226,  488,  491 

Avalon  Dam   383,  384 

Babcock,  E.  S 391 

Baker,  Ira  0 507 

Baker,  M.  N 123 

Bale,  M.  Powis 562 

Banks  of  Canals,  Side  Slopes  and  Top  Widths  of 154 

Bannister,  C.  K 348 

Bari  Doab  Canal,  Drainage  Diversion 268 

Rapids   266 

Barr,  W.  M 563 

Barrois,  J 311 

Barrows,  H.  K 89 


INDEX  593 

PAGE 

Bascuie     48g 

Bazin,  M Sg 

Bear  River  Weir 180 

Canal,  Cross-section  in  Rock 160 

Escapes 242 

Fall    263 

Iron  Aqueduct   277 

Regulator  Gates  ....    221,  237 

Trap  Sluice  Gates    221 

Valley  Dam 416471 

Beetaloo  Dam 44g,  504 

Belle  Fourche,  Automatic  Wasteway  Gate    226 

Dam     381 

Belubula  Dam,  Australia    476 

Beresford,  J.  S 2g,  33,  299 

Betwa  Canal,  Drainage  Diversion 268 

Dam 458 

Automatic  Sluice  Gate    489 

Bhatgur  Dam   444,  49 1 ,  496 

Bjorling,  P.  R 563 

Borings  on  Canal  Locations 134 

Boston  Water  Works  Dam 370 

Bouzey  Dam 414 

Bovey,  Henry  T 352,  507,  563 

Bowlder  and  Brush  Weirs    1 65 

Bowman  Dam    394 

Breast  Water-wheels 526 

Bresse,  M 563 

Brush  and  Bowlder  Weirs    165 

Buck  Scraper    558 

Buckley,  R.  B 33,  41,  46,  48,  57,  263,  31 1, 507 

Bucket  Water  Engines    527 

Buford-Trenton  Pumping  Plant    554 

Butler,  W.  P 116 

Buttressed  Masonry  Walls 474 

By-pass  Feeder,  Umatilla  Canal    246 

Calloway  Canal,  Cross-section 155 

Distributary  Heads    305 

Escapes    242 

Regulator 232 

Weir   168 

Canal  Alignment    127 

Ganges  Canal  as  an  Example    135 

Obstacles  to    132 

Santa  Ana  Canal  as  an  Example 143 

Turlock  Canal  as  an  Example 138 


594  INDEX 

PAGE 

Canal  Banks,  Side  Slope  and  Top  Width  of 154 

Cross-sections,  Form  of 152 

Rock 1 60 

Subgrade   155 

and  Diversion  Works:  Works  of  Reference 311 

Distributaries    296 

Grades  for  Given  Velocities  149 

Head,  Arrangement  of 231 

Limiting  Velocity  in 149 

Ibrahimia    122,  457 

Lined  Cross-section  of 156 

Locations,  Borings  on     134 

Trial  Pits  on    1 34 

Minidoka 385 

Steel-lined 159 

Subgrade,  Cross-section  of 155 

Survey,  Permanent  Marks  on    135 

System,  Parts  of 1 25 

Velocity  in 149,  150 

Water,  Measurement  of    85 

Methods  of  Measurement  of 86 

Work,  Sidehill 133 

Works,  Maintenance  and  Supervision  of 560 

Canals  Absorption  in    30 

Cross-section  of    148,  151 

Curvature  on    134 

Deltaic .'  .  .  .  1 23 

Dimensions  and  Cost  of  some  Perennial  123 

Efficiency  of ' 299 

Inspection  of v 562 

Inundation    120 

Limiting  Velocity  on 149 

Navigation  and  Irrigation 119 

Perennial . ". 123 

Prevention  of  Sedimentation  in 42 

and  Reservoirs,  Amount  of  Absorption  in 30 

Slope  and  Cross-section  of    148,  150 

Sub- 107 

Survey  of 1 28 

Works  of  Reference 311 

Canvas  Dam 333 

Carlsbad  Project 384 

Carmel  Dam,  Wasteway 487 

Carpenter,  Prof.  L.  G 32,  52,  57,  80,  85,  90 

Casing,  Stove-pipe,  for  Drilled  Wells   101 

Castlewood  Dam    394 

Cautley,  Col.  Sir  Proby  T 311 


INDEX  595 


Cavour  Canal,  Inverted  Siphon  under  River  Sesia 292 

Cement    430 

Wash    435 

Centrifugal  Pumps 511,  546 

Pumping  Plants 550 

Chamberlin,  T.  C 1 16 

Chanoine  Movable  Shutters 221 

Check-Levees,  Flooding  by 325 

Checks,  Ditch  and  Furrow 333 

Chemical  and  Physical  Properties  of  Water    58 

Treatment  of  Alkali  Soil 36 

Chezy's  Formula  of  Flow 62,  340 

Chittenden,  Lieut.  H.  M 223,  311 

Church,  Irving  P 90,  507 

Chutes  of  Wood  ...      264 

Cippoletti's  Formula  of  Flow  over  Trapezoidal  Weirs 79,  83 

Clerke,  Sadasewjee  and  Jacob .   507 

Coefficient  of  Friction  in  Masonry    403 

Cohoes  Iron  Rollerway  Weir 196 

Cold  Spring  Dam 369 

Colorado  River  Weir  at  Yuma 175,214 

Wooden  Pipe    346 

Conconully  Dam    504 

Concrete    428 

Pipes    .  349 

Reinfoiced,  Weir 200 

Weir,  Ashlar  Facing    194 

Construction,  Cost  of 506 

Details  of    431 

Contour  Topographic  Survey 130 

Contract  Prices,  Reclamation  Service 585 

Contracts  and  Specifications 440 

Core  Walls,  Masonry 367,  369 

Foundation  of 366 

Corbett  Weir 201 

Cost  of  Artesian  Well  Drilling 95 

Construction  506,  585 

Irrigation 4,  5 

and  Dimensions  of  Perennial  Canals    123 

Pumping    555 

Storage  Reservoir 360 

Unit  on  Reclamation  Works 584 

Craig,  James ....     21 

Cramer,  C.  B 33 

Crib  Dams    392 

Foundations  for  Masonry  Weirs 192 

and  Pile  Foundations  for  Masonry  Weirs • 191 


INDEX 


Crib  and  Rock  Weirs 1 79 

Weirs,  Construction  of  179 

Cribs,  Gathering,  for  Water 107 

Cribwork,  Underground 106 

Crops,  Duty  of  Water  for ^2 

Crossings,  Level 270 

Siphon 292 

Cross  River  Dam 434 

Cross-section  of  Bear  River  Canal  in  Rock 161 

Calloway  Canal   155 

Canals J48,  i  S l 

Canals,  Form  of 152 

Canals  in  Rock    1 60 

Canal  with  Subgrade    155 

Lined  Canal 156 

Santa  Ana  Canal  in  Rock    146 

Turlock  Canal  in  Rock    161 

Umatilla  Canal    161 

Various  Canals 152 

Croton  Dam,  New,  at  Cornell's,  N.  V 426,  433,  447 

Weir    192 

Crushing,  Stability  against,  in  Masonry  Dams   404 

Cultivation  by  Irrigation,  Theory  of 319 

Culverts 289,  294 

Current  Meters : 72 

Acoustic 73 

Haskell 72 

Price : 73 

Rating  the 76 

Use  of : ....     75 

Curved  Dam,  Design  of    418 

Masonry  Dam    4*5 

Curvature  on  Canals 134 

Cusec 47 

Cuts,  Drainagee 268 

Dam,  Ashti  372 

Ash  Fork    474,  47$ 

Assuan 457 

Austin 462 

Avalon    383 

Bear  Valley    -  .416,  471 

Beetaloo 449>  5°4 

Belle  Fourche    380 

Belubula 476 

Betwa 458 

Bhatgur    444,  49r>  496 


INDEX  597 

PAGE 

Boston  Water  Works 370 

Bouzey    414 

Bowman 394 

Canvas    333 

Carmel,  Wasteway  of 487 

Castlewood 394 

Cold  Spring 369 

Combined  Earth  and  Hydraulic-fill    378 

Conconully 504 

Cross  River    434 

Croton,  New,  at  Cornell's 426,  433 

Design  of  Curved    418 

Earth  with  Masonry  Retaining  Wall   382 

East  Park 477 

Ekruk   .382 

Folsom    4<  2,  496 

Furens 442 

Geelong    428 

Gran  Cheurfas 443 

Habra   414 

Hydraulic-fill   377 

Kabra   " 382 

Kalegh    .  .  .   377 

Kingman    438 

La  Grange  4°° 

La  Mesa 378 

Lake  Fife  -   474 

Loose  Rock  with  Masonry  Retaining  Walls 394 

Lower  Otay  •   39 1 

Meer  Allum    474 

Minidoka 385 

Monument  Creek    371 

New  Croton,  Cornell's,  N.  Y 426,  433,  447 

Olive  Bridge    426,  434 

Periar 448,  486,  493 

Profile  of 410 

Profile  Type  for  Masonry    409,  410 

Puentes 412 

Remscheid    450 

Roosevelt    466,  486,  495,  506 

San  Fernando    437 

San  Leandro    377 

San  Mateo 450,  503 

Sante  Fe 372,  487 

Shoshone    417,  470 

Sodom 425,  432 

Specifications 573 


INDEX 

PAGE 

Dam,  Spier  Falls , '. 430,  464 

Steel    478 

Sweetwater 416,  452,  486,  499 

Tansa 444 

Titicus    369 

Tyler  .                                                                 378 

Upper  Otay 472 

Vyrnwy 456,  502 

Wachusett    500 

Walnut  Grove 389 

Zola 416,  471 

Dams,  Asphalt  Lining  and  Cement  Wash   435 

Buttressed  and  Arched 474 

Cement    430 

Classes  of N 360 

Concrete    428 

Construction  in  Flowing  Streams 438 

Crib    392 

Curved  Masonry    415 

Design  of  Curved  Masonry    417 

Overfall 421 

Details  of  Construction  of  Masonry    431 

Dimensions  of  Earth   364 

Diversion 208 

Earth 363 

Masonry  Core  Walls  in 369 

Material  of    ' .  376 

Puddle  Trenches  in   371 

Walls  and  Faces  of 370 

Slope  and  Paving  of 380 

Earth  and  Loose-rock  383 

Examples  of  Masonry 440 

Failure,  Causes  of    363,  41 1 

and  Faulty  Design  of 396 

Foundations  of  Masonry 424 

Earth    365 

Height  of 410 

Inlet ;   for  Drainage 266 

Limiting  Pressures  in  Masonry 406 

Loose-rock 387 

Masonry,  Material  of    426 

Molesworth's  Profile  Type  of 409 

Overfall   420 

Puddle  Walls  and  Faces  of  Earth  370 

Rock-filled 386 

Steel-core 391 

Rubble  Masonry    430 


INDEX  599 

PAGE 

Dams,  Springs  in  Foundations  of 366 

Stability  against  Crushing    404 

of  Gravity 400 

of,  against  Overturning 406 

against  Sliding    402 

Temperature  Changes 415 

of,  against  Upward  Water-pressure 411 

Steel   334,478 

Steel-core,  Rock-filled 391 

Submerged    437 

Theory  of  Masonry 399 

Top  Width  of 410 

Wegmann's  Profile  Type  of 410 

Wide-crested 420 

D'Arcy's  Formula  for  Flow 62,  341 

Darton,  N.  H 92,  117 

Davis,  A.  P 46 

Deakin,  Alfred 46,  57 

Delocre,  M 417 

Del  Norte  Canal  Regulator  Gates 291 

Deltaic  Canals    123 

Derout  Regulator 122 

Desert-land  Grants 131 

Deny,  J.  D 311 

Diamond-Drilling * 357 

Dickens,  Col.  C.  H.,  Formula  for  Runoff    16 

Discharge  over  Weirs,  Table  of 80 

of  Pipes 338 

of  Streams,  and  Table  of 18,  65 

Flood    17 

Mean    21 

in  Seasons  of  Minimum  Rainfall   20 

of  Waste  Weirs    482 

Western  Rivers 20 

Disposal  of  Sewage 107 

Distributaries,  Capacities  of 302 

Design  of 297 

Diagram  Illustrating 297,  298 

Dimensions  of 302 

Efficiency  of    299 

Huntley  Canal    298 

Location  of 296 

Object  and  Types  of 296 

Distributary  Channels  in  Earth 303 

Heads,  Galloway  Canal,  Cal 305 

of  Masonry 310 

of  Wood 304 


600  INDEX 


Distributary  Pipes  of  Iron,  Steel,  or  Wood  v 336 

Capacities  of 286 

Distribution  of  Rainfall  in  Detail    & 

Water,  Rotation  in 55 

Ditch  Checks    333 

Diversion  and  Canal  Works,  Works  of  Reference    311 

Dams   2o£ 

Line 126 

Weirs 164 

Works    126 

Divisors,  Water    89 

Drainage 30 

Crossing  at  Level 270 

Cuts 268 

Diversion,  Bari  Doab  Canal,  India 268 

Betwa  Canal,  India    268 

Inlet  Dams  for 268 

Works    266 

Works  of  Referencee 46 

Dredges   560 

Drilling  Artesian  Wells 35  7 

Diamond  Machines  for 98 

Manner  of    97 

Process  of 100 

Du  Bois,  A.  J ' 90,  312,  3^2,  508,  563 

Duty  of  Sewage    112 

Water 47 

per  Acre-foot 53 

for  Crops,  Various   52 

Linear  and  Areal 54 

Measurement  of 50 

Reference  Works  on    57 

per  Second-foot 51 

Table  of 51 

Units  of  Measure  of 47 

Works  of  Reference 57 

Dyas,  Col.  J.  H 256 

Dyer,  C.  W.  D 90 

Earth  Dam,  Ashti    372 

Boston  Water  Works 370 

Cold  Spring,  Oregon   369 

Ekruk 382 

New  Croton,  at  Cornell's    368 

Santa  Fe,  N.  M 372 

Titicus,  N.  Y 3^ 

Dams,    Construction  of 374 


INDEX  60 1 

PAGE 

Earth  Dams,  Cost  of 507,  585 

Dimensions  of 364 

or  Embankments 363 

Puddling    374 

Failures  of .  .  363,  396 

Foundations  of   365 

Masonry  Core  Walls  in 309 

Trenches  in    372 

with  Masonry  Retaining  Wall 382 

Materials  of 3/6 

Puddle  Walls  and  Faces 370 

Distributary  Channels  in 303 

Evaporation  from 27 

Embankment,  Homogeneous 367,  372 

Slope  and  Paving  of 380 

and  Loose-Rock  Dams 383 

Failures  and  Faulty  Design  of 396 

Waters,  Sources  of 91 

Earthwork,  Cost  of    .  .  507,  585 

Shrinkage  of   159 

East  Park  Dam    ....   477 

Echeverry,  B.  A .  .  .  .  1 56,  3 1 1 

Efficiency  of  a  Canal 2 

Egypt,  Area  Irrigated  in  122 

Canals 121 

Ekruk  Dam .382 

Electric  Current  Meters    72 

Elevators,  Mechanical  Water 510,  556 

Embankment,  Construction  of 376 

Cost  of   .  507,  585 

Earth  Dams  or 363 

Homogeneous   367,  372 

Hydraulic  Fill 377 

Material 376 

with  Masonry  Retaining  Wall 382 

of  Sand 377 

Slope  and  Paving  of 380 

Energy,  Equivalent  Units  of 545,  546 

Engineering  News 117 

Engines,  Alcohol  Pumping 542 

Gasoline  Pumping  513,  542 

Hot-air  Pumping    510,  542 

Pumping    551 

Steam  Pumping    511 

W'ater  Pressure 537 

Fscapes    .                                                                                                                ...   239 
Bear  River  Canal,  Utah    242 


602  INDEX 


Escapes,  Galloway  Canal,  Cal 242 

Goulburn  Canal,  Australia 244 

Heads,  Design  of 242 

Highline  Canal,  Col 242 

Location  and  Characteristics  of 240 

Qushesha 122 

Turlock  Canal,  Cal 242 

Eucalyptus  as  Preventive  of  Fevers 45 

Evans,  John    , 33 

Evaporating-pan 24 

Evaporation,  Amount  of 25 

Effect  of,  on  Water  Storage    31 

from  Earth    27 

Measurement  of  23 

Phenomena   23 

from  Snow  and  Ice    25 

Table  of  Depth  of   26 

Works  of  Reference 33 

Evaporometer,  Piche 25 

Excavating  Machines    559 

Excavation,  Cost  of  Earth    585 

Fall,  Agra  Canal,  India 286 

Bear  River  Canal,  Utah 161 

Interstate  Canal    262 

Lower  Yellowstone  Canal 264 

Notched  Crest ' 260 

Turlock  Canal,  California 270 

Uncompahgre  Canal,  Notched 259 

Fall  of  Wood,  Simple  Vertical  263 

Wooden,  with  Water-cushion 263 

Falls  of  Masonry    264 

and  Rapids 255 

Retarding  Velocity  of  Approach  to,  by   contracting  Channel  above 257 

by  Flashboards    256 

by  Gratings    257 

Falling  Sluice  Gates 221,  224 

Water,  Power  in   524 

Scouring  Effect  of 183 

Fanning,  J.  T 16,  21,  89,  352,  403,  507,  544,  563 

Farms,  Sewage 114 

Fernow,  B.  E 27 

Fay  Lake  Reservoir  Outlet  Gates 504 

Fayoum 122 

Fertilizing  Effects  of  Sediment 44 

Sewage no 

Fevers    . 1 1  * 


INDEX  603 

PAGE 

Fevers,  Malarial 44 

Finkle,  F.  C 352 

Fitzgerald,  Desmond 17,  21,  33 

Flashboard  or  Open-frame  Weirs 168 

Regulators  of  Wood    232 

Flashboards  on  Fall  Crest  to  Retard    2>6 

Flinn,  A.  D 90 

Flood  Discharges  of  Streams 17 

Flooding  by  Check-levees   325 

and  Furrow  Irrigation  Combined   328 

of  Sidehill  Meadows 324 

by  Squares    326 

by  Terraces    327 

Flow,  Available  Annual,  of  Streams  21 

Chezy's  Formula  of    62 

Kutters  Formula  of 62 

and  Measurement  of  Water  in  Open  Channels,  Works  of  Reference  on .  .    89 

in  Open  Channels,  Formulas  of 61 

of  Water  in  Pipes   338 

Formulas  of 339 

Measurement  of 350 

Tables  of 340 

Units  of  Measure  of 47 

Velocities  of 65 

Flume,  Highline  Canal,  Col 274 

over  Mill  Creek,  Santa  Ana  Canal    143 

San  Diego,  Cal 274 

Santa  Ana  275 

Stave  and  Binder  275 

Trestles   276 

Flumes  and  Aqueducts 272 

Flumes,  Construction  of t 274 

Rating 88 

Reinforced  Concrete 283 

Sidehill 274 

Stave  and  Binder    275 

Flynn,  P.  J 57.  9°,  256,311,352 

"  Flow  of  Water,"  by 62,  340 

Folsom  Canal,  Hydraulic  Lifting  Gate 239 

Dam 462,  496 

Foote,  A.  D 57,87 

Foote's  Water  Meter 87 

Formula,  Chezy's 62 

Francis'    78 

of  Flow  of  Water  in  Open  Channels  62 

Pipes 339 

Kutter's    , 62,  339 


604  INDEX 

PAGE 

Formula  of  Maximum  Runoff    16 

Fortier,  Samuel 33,  52,  57,  352 

Foundations  of  Dams,  Exploring  for  Bed-rock 357 

Springs  in    366 

Earth  Dams 365 

Masonry  Core  and  Puddle  Wall    366 

Dams 424 

Preparing 424 

France,  Area  irrigated  in    2 

Francis'  Formulas  of  Flow  over  Weirs 78 

Francis,  J.  B 78,  405,  483,  507 

French  Movable  Weirs  of  Iron    177 

Scraper 558 

Fteley,  A 5°7 

Furens  Dam 442 

Furrow  Checks 333 

and  Flooding  combined 328 

Irrigation 327 

Furrows,  Irrigation  by  Small     320 

Ganges  Canal  as  an  Example  of  Canal  Alignment 135 

Headworks  and  Plan  of    228 

Kali  Nadi  Aqueduct    282 

Ranipur  Superpassage 135,  286 

Regulator  Gates 234 

Rutmoo  Level  Crossing 136,  271 

Solani  Aqueduct 136,  279 

Garland  Canal  Turnouts    -  .  .   31 1 

Gasoline  Engines  513,  542 

Gas  Producer  for  Pumping ...   545 

Gate,  Automatic  Wasteway    225 

Balanced  Sluice 495 

Chamber 498 

Regulator  Raised  by  Screw   235 

Windlass    234 

Towers    498 

Examples  of    500 

Gates,  Automatic  Weir 223,  488,  491 

Electrically  Operated 5°<> 

Falling  Sluice    221 

Hydraulic  Lifting 239 

Inclined  Falling   236 

Regulator 234,  239 

Sand 250 

Taintor  Wasteway  , 246 

Gathering-Cribs  for  Water 106 

Gauge  Heights,  Weir 8° 


INDEX  605 

PAGE 

Gauging  Car 74 

Rainfall 1 1 

Stations    74 

Stations,  Rating  the 75 

Stream  Velocities 70 

Gearing,  Regulator  Gates  raised  by 235 

Geelong  Dam    428 

Geology  of  Reservoir  Site 359 

Gila  River  Valley,  Precipitation  in 8 

Glassford,  Lieutenant  W.  A 21 

Goulburn  Canal,  Escapes 244 

Regulator  Gates    236 

Iron  and  Masonry  Drop-gate  Weir 197 

Gould,  E.  Sherman 352,  507 

Grade  for  given  Velocities  on  Canals 149 

Grading  Machines   559 

Gran  Cheurfas  Dam 443 

Grand  River  Canal,  Big  Drop 264 

Granite  Reef  Regulator 229 

Sluice  Gate 219 

Sluiceway    21^ 

Weir 202 

Gratings  to  Retard  Velocity  of  Approach  to  Falls    .                             2^7 

Gravity  Dams,  Stability  of 400 

and  Lift  Irrigation 1 18 

Greaves,  Charles    28,  33 

Greeley,  Gen.  A.  W 21 

Green,  J.  S 90 

Griffiths,  J.  A 518,  563 

Ground,  Preparation  for  Irrigation 322 

Water,  Motion  of 91 

Habra  Dam 414 

Hall,  Wm.  Ham 57,  u 7,  3",  352.  5°7 

Hamlin,  Homer    117 

Haskell  Current  Meter    72 

Hay,  Robert 117 

Hazen,  Allen 92 

Heads,  Masonry  Lateral 310 

Wooden  Lateral   304 

Headworks  of  Arizona  Canal,  Plan  of    215 

Arrangement  of 231 

Character  of 163 

Ganges  Canal,  India      .  . 229 

Location  of 162 

Health,  Effects  of  Sewage  on 1 1 1 

Irrigation  on    44 


606  INDEX 


Henares  Canal  Iron  Aqueduct,  Spain 278 

Weir,  Spain 194 

Herschel,  Clemens  311,  350 

Highline  Canal,  Bench  Flume   274 

Escapes 242 

Sand  Gate    250 

Hilgard,  E.  W 37,  46,  377 

Hill,  Robert  T 117 

Hobart,  E.  F 507 

Hollister,  J.  B 90 

Holyoke  Weir  208 

Horton,  R.  E 80,  90 

Hot-air  Pumping  Engines 5 10,  541 

Hoyt,  J.  C ...     89 

Hughes,  Samuel   563 

Humphreys  and  Abbott    70 

Hurdy-gurdy 526 

Hydraulic-fill  Embankment  or  Earth  Dam   377,  378 

Hydraulic  Lifting  Regulator  Gate,  Folsom  Canal,  Cal 239 

Motors 526 

Rams .527,  539 

Ibrahimia  Canal,  Egypt    :  ...  122,  457 

Ice,  Evaporation  from 25 

Stream  Measurement  under 89 

Inch,  Miner's    48,  87 

Statute  or  Module : 86 

India,  Precipitation  in 7,11 

Area  Irrigated  in 2 

Indian  Type  Weirs    1 70 

Inlet  Dams  for  Drainage    268 

Inspection  of  Irrigation  Works    562 

Inundation  Canals 1 20 

Interstate  Canal  Falls 262 

Flume 284 

Siphon    295 

Sluiceway 245 

Inverted  Siphons    289 

Hurron  Torrent,  Sirhind  Canal 293 

Kao  Torrent,  Soane  Canal 291 

Sesia  River,  Cavour  Canal 292 

of  Masonry 291 

Investment,  Value  of  Irrigation  as  an 3 

Iron  Aqueducts 276 

Agra  Canal 286 

Bear  River  Canal .  .   277 

Henares  Canal 276 


INDEX  607 

PAGE 

Iron  Aqueducts,  and  Steel  Pipes 343 

Weirs 196 

Movable 176 

Rollerway 196 

Irrigated  Area  in  United  States  6 

Irrigation,  Alkali,  Effects  of  on 34 

Cost  and  Returns  of 4 

Cultivation  by 319 

Effect  on  Health  of  Sewage in 

Engineers,  American  Society  of  311 

Extent  of  2 

by  Flooding  by  Checks  325 

and  Furrows  combined 328 

by  Furrows 327 

Gravity i ;  8 

Harmful  Effects  of  44 

Incidental  Value  4 

Lift  1 18,  509 

Malarial  Effects  of  44 

of  Meadows  by  Flooding 32  [ 

Meaning  of i 

and  Navigation  Canals 1 19 

Period 54 

Quantity  of  Water  per 56 

Preparation  of  Ground  for  322 

Pumping  or  Lift  509 

Relation  of  Rainfall  to 7 

Sewage  1 09 

by  Small  Furrows  330 

Subsurface 334 

by  Terraces  327 

Theory  of  Cultivation  by 319 

Tools  ..  .---557 

Value  as  an  Investment  3 

Windmills  for ^23 

Works,  Classes  of 1 18 

Control  of 2 

Sources  of  Impairment  of  561 

Irrigating  Machines,  Value  of  Windmills  as  523 

Period,  Quantity  per  53 

Italy,  Area  Irrigated  in  2 

Precipitation  in 7 

Jackson,  Louis  D'  A 117 

Jacobs,  Arthur 508 

Jaffa,  M.  E 38,  46 

Kabra  Dam 382 


608  INDEX 


Kalegh  Sand  Embankment,  India 377 

King,  Prof.  F.  H 57,  352 

Kingman  Submerged  Dam 438 

Krantz,  J.  B     400,  416,  508 

Kutter's  Formula  of  Flow 62,  340 

Tables  for  Use  with 63 

La  Grange  Dam 460 

Laguna  Weir,  Colorado  River 1 75,  2 14 

La  Mesa  Dam    378 

Lake  Fife  Dam 474 

McMillan    .384 

Land  Grants,  Desert     131 

Percentage  of  Waste    55 

and  Water  Supply,  Relation  between   126 

to  Reservoir  Site 353 

Landreth,  O.  H 524 

Laterals,  Capacities  of 302 

Dimensions  of    302 

Masonry  Heads  to 310 

Wooden  Heads  to    304 

Latha 5X5 

Law,  Reclamation 564 

Leaching  of  Alkali  Soil   38 

Leasburg  Regulator  Gates 236 

Sand  Gates    253 

Weir ' 19° 

Level  Crossings  of  Drainage 268 

Rutmoo ... 136 

Turlock  Canal 270 

Lever,  Wooden  Regulator  Gate  raised  by 234 

Levinge,  H.  C 311 

Lift  and  Gravity  Irrigation 1 18 

Irrigation  or  Pumping 5°9 

Weir,  Rolling 1 77 

Limiting  Pressures  in  Masonry  Dams    4°6 

Linear  Duty  of  Water 54 

Location  and  Characteristics  of  Escapes    240 

of  Distributaries 296 

of  Headworks IO2 

Survey,  and  Alignment  of  Canals 127,  128 

Loose-rock  and  Earth  Dams   •    •  •  383 

Failures  and  Faulty  Design  of 396 

Dams •  387 

Loughridge,  R.  H •  331 

Lower  Ganges  Canal,  Nadrai  Aqueduct,  India    282 

Lower  Otay  Dam 391 


INDEX  609 

PAGE 

Lower  Yellowstone  Canal  Falls 264 

Level  Crossing    270 

Siphon 294 

Turnouts   310 

Wasteway    245 

Weir 182 

McCall's  Ferry  Dam   428,  433,  434 

McCulloh,  Walter    .  .  .  508 

McMasters,  John  B 508 

McMillan  Lake    .384 

Machines,  Drilling 98 

Excavating .  559 

Pumping,  Choice  of    512 

Mahan,  F.  A .  .  .  563 

Mahanuddy  Sluice  Shutters   223 

Maintenance  of  Canal  Works    560 

Malarial  Effects  of  Irrigation 44 

Manning,  Robert  117 

Masonry  Aqueducts 279 

Coefficient  of  Friction  in    403 

Cores .  .367,  369 

Foundation  of 366 

Dams  of  Concrete  428 

Cost  of  Construction  of 507 

of  Cement 430 

Construction  in  Flowing  Streams    430 

Curved 415,  418 

Details  of  Construction 431 

Examples  of    440 

Failure  and  Causes  of 411 

Foundations  of 424 

Limiting  Pressures  in 406 

Material  of    426 

Overfall  Type 420 

Profile  Type  for 409,  410 

of  Rubble    430 

Stability  of 400 

Crushing    404 

Overturning    406 

against  Sliding    402 

Temperature  Changes  ....    415 

Upward  Water  Pressure 411 

Theory  of    399,  409 

Falls 264 

Inverted  Siphons 289 

Lateral  Heads   310 


6lO  INDEX 

PAGE 

Masonry  Rapids 266 

Retaining  Wall,  Embankment  with 382 

Turnouts 310 

Walls,  Buttressed  and  Arched 474 

Weir  of  Rubble 195 

Weirs 188 

Founded  on  Piles 190 

Piles  and  Cribs 191 

Wells    192 

Open  Indian  Type 170 

Maxwell,  J.  P 33 

Mead,  Elwood    57 

Meadows,  Sidehill  Flooding  of 324 

Means,  Thomas  H 36 

Measure,  Unit  of,  for  Water  Duty  and  Flow 47 

Measurement  of  Canal  Water    85 

Methods  of    86 

Evaporation 23 

and  Flow  of  Water,  Works  of  Reference    89 

Stream  under  Ice    89 

Water  Duty 50 

in  Pipes    350 

Measures  of  Water,  Table  of  Units  of   48 

Measuring  Apparatus,  Requisites  of  a 85 

Stream  Velocities 70 

Weirs 77 

Rectangular 77 

Medley,  Lt-Col.  J.  G 311 

Meer  Allum  Dam 474 

Merriman,  Mansfield 508 

Meters,  Current 72 

Rating  the  76 

Use  of 75 

Foote's  Water 87 

Venturi  Water 350 

Miner's  Inch 48,  87 

Minidoka  Project  and  Dam 385 

Regulator  Gates 236 

Module,  or  Statute  Inch 86 

or  Water-Measuring  Apparatus 85 

Molesworth,  Guilford  L 409 

Profile  Type  for  Masonry  Dam    409 

Moncrieff,  C.  C.  S 311 

Monument  Creek  Dam 371 

Mot 5I5 

Motion  of  Ground  Water 91 

of  Water   .  60 


INDEX  6ll 


Motive  Power  for  Pumps 510 

Motors,  Water    526 

Movable  Weirs 1 76 

Mulching  Alkali  Soil  38 

Mullin,  Lt.-Gen.  J 90,  3 1 1 

Murphy,  E.  C .  .85,90,523,563 

Murray,  Stuart  312 

Nadrai  Aqueduct,  Lower  Ganges  Canal,  India    282 

Navigation  and  Irrigation  Canals 1 19 

Nettleton,  E.  S 117 

Newark  Weir    206 

Newbrough,  W 312 

New  Croton  Dam,  Cornell's,  N.  Y 426,  433,  447 

Newell,  F.  H ..15,  22,33,57,90,  117 

Nile  Inundations    1 20 

Nilometer    74 

Noria 515 

Norwich  Water  Power  Go's.  Weir 191 

Notched  Fall  Crest    260 

Ogee-shaped  Weirs    185,  196 

Okanogan  Canal  Rapids 266 

Olive  Bridge  Dam   426,  434 

Orme,  Dr.  S.  H 45,  1 1 7 

Otay  Dam,  Lower 39 1 

Upper.  .  .   472 

Outlet  Gate,  Roosevelt  Dam 506 

Vertical  Lift 496 

Sluices    496 

Examples  of    500 

Overfall  Dams    420 

Overshot  Water  Wheel 5  26,  531 

Overturning,  Stability  of  Dams  against 406 

Paecottah 515 

Parker  Bear-trap  Gate    223 

Paving  of  Embankment    380 

Pecos  Dam   383,  384 

Valley,  Precipitation  in  9 

Pelletreau,  M 417 

Pelton   Water-wheel    526,  534 

Pequannock  Weir  at  Newark 206 

Percentage  of  Waste  Land  ....     55 

Percolation,  Amount  of 28 

Prevention  of    30 


6l2  INDEX 

PAGE 

Perennial  Canals 122 

Dimensions  and  Cost  of 123 

Periar  Dam 448,  486,  493 

Permanent  Marks  on  Canal  Surveys    133 

Persian  Wheel 514 

Pruenix,  Precipitation  at 12 

Physical  and  Chemical  Properties  of  Water    58 

Piche  Evaporometer    25 

Pile  Foundations  for  Masonry  Weirs    190 

Weirs 166 

Pipe  Irrigation,  Works  of  Reference 352 

Pipes,  Concrete 349 

Construction  of  Wooden 347 

Flow  of  Water  in 338 

Formulas  of  Flow  in    339 

Iron  and  Steel 343 

Main  and  Distributing    336 

Measurement  of  Water  in 350 

Reinforced  Concrete    349 

Steel  343 

Sub-irrigation 336 

Tables  of  Flow  in 340 

Wooden  Stave 346 

Works  of  Reference  on 352 

Plant  Growth,  Relation  of,  to  Soil  Texture 315 

Water    .  .  .   313 

Plants  Suitable  for  Growth  in  Alkaline  Soil    38 

Poncelet  Water-wheel    528 

Powell,  J.  W 117 

Power,  Cost  of,  for  Pumping 555 

Equivalent  Units  of    547 

of  Falling  Water   524 

-Pumped  Wells 103 

Precipitation  by  River  Basins,  Table  of 10 

States,  Table  of '. 12 

Works  of  Reference  on 21 

Pressure,  Atmospheric 60 

Limiting,  in  Masonry  Dams   406 

of  Water 59 

Price  Current  Meter    73 

Producer  Gas  Power  545 

Profile  of  Dam 410 

Type  for  Masonry  Dam 409,  410 

Public  Lands,  Right  of  W7ay  on 131 

Puddle  Trench   371 

Walls    367,  370 

and  Faces 370 


INDEX  613 

PAGE 

Puddle  Walls,  Foundations  of 366 

Puentes  Dam ...  412 

Pulsometers 556 

Pumping,  Cost  of 555 

Engines    .  .  .  551 

Alcohol 541 

Gasoline 541 

Hot-air 541 

Steam 552 

or  Lift  Irrigation    509 

Machinery,  Reference  Works 562 

Machines,  Choice  of    512 

Plants,  Examples  of  Centrifugal    550 

Steam 552 

Willixton,  N.  D 554 

by  Steam-power 543 

Pumps,  Animal-power 514 

Centrifugal    511,  546 

Chain 512 

Direct-acting 512 

Fly-wheel 512 

Force    510 

Gas 510 

Gasoline 510 

Hot-air 510 

Hydro-electric 511 

Lift 510 

Motive  Force  for    510 

Rotary 510,  546 

Steam 511 

Water-power 510 

Wind-power    515 

Queshesha  Escape  122 

Rafter,  Geo.  W 117 

Rainfall 7 

Discharge  of  Streams  in  Seasons  of  Minimum    20 

Distribution  in  Detail   8 

Gauging i  r 

Great 9 

Increase  of,  with  Altitude 8 

Relation  of,  to  Irrigation 7 

Runoff 15 

on  River  Basins   1 1 

Statistics,  General    7,10 

by  States   .  • 1 1 


614  INDEX 

PAGE 

Rainfall,  Works  of  Reference  on 21 

Rams,  Hydraulic    527,  539 

Ranipur  Superpassage  .  . . 135,  286 

Rapids,  Bari  Doab  Canal,  India 266 

and  Falls 255 

Masonry 266 

Okanogan 266 

Wooden 264 

Rating  Current  Meter 76 

Flumes    88 

Gauging  Station    76 

Reclamation  Law 564 

Scope  of 567 

Service    312,  508 

Lateral  Heads 308 

Reinforced  Concrete  Flumes    283 

Specifications  of 573 

Unit  Cost  on   584 

Wasteways 244 

Rectangular  Measuring  Weir 77 

Conditions  of  Using  the    79 

Pile  Weirs 7 166 

Reference  Works:    Alkali,  Drainage,  and  Sedimentation    46 

Application  of  Water  and  Pipe  Irrigation    352 

Artesian  Wells    117 

Diversion  and  Canal  Works 311 

Duty  of  Water    57 

Evaporation,  Absorption,  and  Seepage 33 

Flow  and  Measurement  of  Water  in  Open  Channels 89 

Precipitation,  Runoff,  and  Stream-flow    21 

Pumping  Machinery 562 

Sewage  Irrigation 117 

Storage  Works    507 

Subsurface  Water  Sources    117 

Regimen  of  Western  Rivers 20 

Regulator  Gates,   Arizona  Canal , 232 

Bear  River  Canal,  Utah    242 

Del  Norte  Canal,  Col 291 

Folsom  Canal,  Hydraulic  Lifting    239 

Ganges  Canal,  India   234 

Goulburn  Canal,  Australia       244 

Granite  Reef 229 

Hydraulic  Lifting 239 

Inclined,  Falling 244 

Leasburg 236 

Lifted  by  Travelling  Winch   235 

Minidoka  Canal 236 


INDEX  615 

PAGE 

Regulator  Gates,  Raised  by  Gearing  or  Screw 235 

Rolling,  Idaho  Canal 236 

Sliding,  Idaho  Canal   236 

Soane  Canal,  India    235 

of  Wood  lifted  by  Lever 234 

Windlass    234 

Regulators,  Galloway  Canal,  Cal •    232 

Classification  of 230 

Form  of    .230 

Relation  of  Weirs  to 227 

Wooden  Flashboard   232 

Reid,  H.  I .117 

Reinold,  E.  K -  491 

Reinforced-Concrete  Canal  Lining 158 

Culverts    294 

Flumes  and  Trestles 283 

Pipes 347 

Siphon 294 

Weir    200 

Remscheid  Dam 45° 

Reservoir  Site,  Character  of 353 

Geology  of    359 

Relation  of,  to  Land  and  Water  Supply    354 

Topography  and  Survey  of 355 

Reservoirs  and  Canals,  Amount  of  Absorption  in 30 

Cost  and  Dimensions  of  some  Storage    360 

Prevention  of  Sedimentation  in    42 

Retaining  Wall  of  Masonry,  Embankment  with 382 

to  Loose-rock  Dam .   394 

Retarding  Velocity  of  Approach  by  Contracting  Channel  above  Fall   257 

Flashboards  on  Fall  Crest    256 

Gratings  on  Fall  Crest   257 

Returns  of  Irrigation 4 

Right  of  Way  on  Public  Lands 131,  312 

Rio  Grande,  Precipitation  on 9 

River  Basins,  Precipitation  on 1 1 

Training  Works 209 

Rivers,  Western,  Discharge  of 21 

Regimen  of 20 

Rock  and  Crib  Weirs    1 79 

Cross-section  of  Canals 160 

Excavation,  Cost  of 588 

Foundations,  Exploring  for    357 

Rock-filled  Dams 386 

and  Crib  Weir    1 79 

Steel-core  Dam 391 

Rollerway  and  Ogee-shaped  Weirs  1 85 


6l6  INDEX 

PAGE 

Rollerway  Weir  of  Iron 196 

Rolling  Lift- Weir 177 

Ronna,  A 312,  508,  563 

Roosevelt  Dam 466,  486,  495 

Outlet  Gates 506 

Specifications  of 573 

Rotation  in  Water  Distribution   55 

Rotary  Pumps    '. 546 

Rubble  Masonry 430 

Weir 195 

Runoff 14 

Amount  of,  and  Tables  of 17, 1 8 

Examples  of 21 

Formulas  for  Maximum 16 

of  Streams,  Table  of    18 

Relations  to  Rainfall   15 

Variability  of 14 

Works  of  Reference 21 

Russell,  T 25 

Rutmoo,  Level  Crossing   13&>  27° 

Ryves.  Col.,  Formula  for  Runoff 16 

Sacremento  Valley,  Precipitation  in    9 

Sakia    515 

Salt  Bush,  Australia    38 

Salt  River,  Rainfall  and  Flood  Height  of 8 

Salt  River  Valley  Project 468 

San  Diego  Flume 274 

San  Fernando  Dam 437 

San  Joaquin  Valley,  Precipitation  in 9 

San  Leandro  Dam 377 

San  Mateo  Dam 429,  450,  502 

Sand,  Embankments  of 377 

Gates 250 

Highline  Canal 251 

Leasburg 253 

Santa  Ana  Canal 252 

Santa  Ana  Canal,  Alignment   143 

lined  Channel   157 

Flume 276 

Sand  Gates    252 

Tunnels    , 158 

Santa  Fe  Earth  Dam 372,  487 

Schuyler,  J.  D . :  435,  504,  508 

Scott,  John  H 312 

Scouring  Effect  of  Falling  Water 183 

Sluices  .  .211 


INDEX  6 1  7 

PAGE 

Scouring  Sluices  Agra  Canal,  India, 212 

Examples  of    212 

Monte  Vista  Canal,  Col 212 

Scraper,  Buck .  558 

Scrapers -557 

Screw  Regulator,  Gate  raised  by 235 

Second-foot   47 

Duty  of  Water  per 51 

Sediment,  Amount  of 41 

Fertilizing  Effects  of 44 

Sedimentation,  Prevention  of,  in  Reservoirs  and  Canals 42 

Reference  Works  on 46 

Seepage  Water    31 

Works  of  Reference 33 

Service  Period 50 

Quantity  of  Water  per 53 

Sesia  Siphon  on  Cavour  Canal,  Italy    292 

Sewage  Application 114 

Disposal 107 

Duty  of    112 

Fertilizing  Effects  of    1 1  o 

Health,  Effect  on 1 1 1 

Irrigation     100 

Laying  out,  Farm    114 

Works  of  Reference    117 

Shrinkage  of  Earthwork 1 59 

Shoshone  Dam   417,  470 

Shutters,  Automatic  Weir 488 

Chanione  Movable 221 

Side  Slopes  of  Canal  Banks 154 

Sidehill  Canal  Work    133 

Turlock  Canal    1 40 

Sidehill  Flooding  of  Meadows 324 

Flumes 274 

Sidhnai  Weir 174 

Silt    40 

Amount  of 41 

Character  of   ». 40 

Siphon  Aqueduct  on  Soane  Canal  under  Kao  Torrent 291 

Crossing,  Interstate  Canal 295 

under  Hurron  Torrent  on  Sirhind  Canal,  India    293 

Inverted,  Sesia  River,  on  Cavour  Canal,  Italy 292 

Siphons    289 

Inverted   289 

Masonry,  Inverted    29 1 

Reinforced  Concrete    294 

Wood,  Inverted   291 


6l8  INDEX 

PAGE 

Sirhind  Canal,  Siphon  under  Hurron  Torrent 293 

Slichter,  C.  S 33,  92,  117 

Sliding,  Stability  against,  in  Masonry  Dams 402 

Slope  of  Canals 148 

Canal  Sides 154 

Embankment 380 

Excessive    255 

Sluice  Gates,  Automatic 221,  226 

Balanced 493 

Bear  Trap  Movable 221 

Falling   221 

Granite  Reef  Weir 219 

Laguna  Weir , 217 

Shutters,  Chanoine  Movable ' 221 

Mahanuddy  Automatic 223 

Sluiceways 211 

Interstate  Canal   246 

Laguna    214 

Sluices,  Outlet    496 

Examples  of    500 

Scouring ...211 

Snow,  Evaporation  from 25 

Soane  Automatic  Sluice  Gates 224,  488 

Canal,  Regulator  Gates 235 

Canal,  Siphon-Aqueduct  under  Kao  Torrent 291 

Weir i72 

Sodom  Dam    .' 425,  432 

Soil,  Depth  of  Water  required  to  Soak 52 

Texture,  Relation  of,  to  Plant  Growth .313 

Solani  Aqueduct,  Ganges  Canal,  India    136,  279 

Sources  of  Earth  Waters 91 

Springs  and  Artesian  Wells 93 

Supply •  -119 

Specifications  and  Contracts 44° 

of  Roosevelt  Dam,  Reclamation  Service    573 

Spier  Falls  Dam 43°>  464 

Spillway  to  East  Park  Dam  ...  477 

Spillways   • •  •  •  •    239 

Spon,  Ernest ! IJ7 

Springs  and  Artesian  Wells    93 

in  Foundations  of  Dams 3^6 

Sources  of    93 

Squares,  Flooding  by 326 

Stanton,  R.  B 388,  436>  5°8 

State  Desert  Land  Grants    I31 

Statistics  of  Rainfall    7,  10,  1 1,  12,  13 

Statute  Inch  or  Module 86 


INDEX  619 

PAGE 

Stave  and  Binder  Flume 275 

Pipes  of  Wood  346 

Steam  Power,  Pumping  by 543 

Pumping  Engines 543 

Plants 552 

Steel  Core  Rock-fill  Dam   391 

Dams 334,  478 

and  Iron  Pipes 343 

Lined  Canal    159 

Stewart,  Henry 312 

Stoney's  Balanced  Sluice-gate 493 

Storage  of  Artesian  Water    96 

Reservoir,  Cost  and  Dimensions  of 360 

of  Water,  Effect  of  Evaporation  on 28 

Works,  Classes  of 353 

Works  of  Reference  on 507 

Storms,  Suddenness  of  Great 1 1 

Stream  Flow,  Works  of  Reference 21 

Measurement  under  Ice 89 

Velocities,  Measuring  or  Gauging 70 

Streams,  Available  Annual  Flow  of 21 

Construction  of  Dams  in  Flowing 438 

Discharge  of r 7,  70 

Flood  Discharge  of 17 

Mean  Discharge  of    21 

Table  of  Discharge  and  Runoff  of 18 

Subcanals 107 

Subgrade  to  Canal  Cross-section 155 

Subirrigation  Pipes 336 

Submerged  Dams 437 

Subsupply  Tunnels 105 

Subsurface  Irrigation 334 

Water  Sources 107 

Subterranean  Water  Tunnel  and  Wells    105 

Suddenness  of  Great  Storms    1 1 

Superpassage 284 

on  Ganges  Canal  over  Ranipur  Torrent    135,  286 

of  Iron,  Agra  Canal,  India   286 

Supervision  of  Canal  Works 560 

Supply,  Sources  of   119 

Supplying-Capacity  of  Wells    102 

Survey  of  Canals    ^128 

Contour,  Topographic '. 130 

Linear  or  Trial  line    128 

Method  of  Canal 1 28 

Permanent  Marks  on     134 

and  Topography  of  Reservoir  Site 355 


620  INDEX 

PAGE 

Sweetwater  Dam    416,  452,  486,  500 

Taintor  Wasteway   246 

Tansa  Dam 444 

Tatils,  or  Rotation  in  Water  Distribution    55 

Terraces,  Flooding  by 327 

Theory  of  Masonry  Dams    399 

Tieton  Canal  Lining 158 

Flumes    283 

Titicus  Dam  369 

Tools,  Irrigation 557 

Topographic  Survey,  Contour 130 

Topography  and  Survey  of  Reservoir  Site 355 

Top  Width  of  Canal  Banks 154 

Towers,  Gate    498 

Training- Works  for  Rivers 209 

Trapezoidal  Weirs  79 

Tables  of  Flow  over 83 

Trautwine,  J.  C 90 

Trench,  Puddle,  in  Earth  Dams 371 

Trestles,  Flume 276 

Trial-line  Survey    128 

Trial  Pits  on  Canal  Locations   134 

Trowbridge,  W.  P 563 

Truckee-Carson  Canal,  Lining    157 

Tunnels  on    148 

Tunneling  for  Water 105 

Tunnels  for  Sub-supply : 105 

Santa  Ana  Canal    146 

Truckee-Carson  Canal 148 

Turlock  Canal 142 

Underground .- 105 

Turbine  Water-wheels 532 

Turlock  Canal  as  an  Example  of  Canal  Alignment 138 

Level  Crossings 270 

Sidehill  Works 140 

Tunnels    142 

Turneaure,  F.  E .   508,  563 

Turnouts,  of  Masonry 310 

Wood    -  3°4 

Tyler  Dam,  Texas •  378 

Tympanum 515 

Umatille  By-pass   ." 246 

Canal  Section 161 

Project,  Cold  Spring  Dam 369 

Uncompahgre  Canal  Fall 259 

Underflow 93 


INDEX  621 

PAGE 

Underground  Cribwork  or  Tunnels 106 

Undershot  Water-wheels 526,  527 

Undersluices 495 

Examples  of    496 

United  States,  Area  irrigated  in 6 

Units  of  Measures  for  Water  Duty  and  Flow 47 

Power,  Equivalents  of    547 

Upper  Otay  Dam 472 

Valve- chambers 498 

Examples  of    .   500 

Variability  of  Runoff 14 

Velocity  of  Approach,  Retarding  by  Contracting  Channel  above  Fall    257 

Flashboards  on  Fall  Crest 256 

Gratings  on  Crest  of  Fall    257 

Limiting,  on  Canals  149 

Velocities  on  Canals  for  given  Grades    149 

Examples  of 150 

of  Flow  in  Canals 65,  148 

Pipes  .  .  .338 

Formula  for 61 

Stream,  Measuring  or  Gauging  70 

Surface  and  Mean 70 

Venturi  Water  Meter 350 

Vernon-Harcourt,  T.  F 312 

Vertical  Fall  of  Wood 263 

Vir  Weir   195 

Vischer,  Huber 418,  508 

Vyrnwy  Dam    456,  502 

Wachusett  Dam   500 

Wagoner,  Luther 418,  508 

Wall,  Norvel  W 117 

Walls,  Core,  in  Earth  Dams 369 

Masonry    474 

Puddle,  in  Earth  Dams 367,  371 

Steel 367 

Walnut  Grove  Dam 389 

Waste  Land,  Percentage  of    55 

Weirs,  Discharge  of  482 

Wasteway  Gate,  Automatic 226 

Taintor 246 

Weirs,  Shapes  of   484 

Wasteways 239 

Carmel  Reservoir 487 

Character  and  Design  of 482 

Classes  of 483 


622  INDEX 


Wasteways,  Examples  of 486 

Location  and  Characteristics  of 240 

Reclamation  Service    244 

Water,  Artesian,  Storage  of    96 

Center  of  Pressure  of 59 

Chemical  and  Physical  Properties  of 58 

Depths  of,  required  to  Soak  Soil 52 

Distribution,  Rotation  in 55 

Divisors    89 

Duty  of 57 

Linear  and  Areal 54 

Measurement  of 50 

Reference  Works  on    57 

Table  of 51 

Units  of  Measure  for 47 

Excessive  Use  of 39 

Factors  affecting  Flow  of 61 

Falls,  Power  in    524 

Flow  of,  in  Pipes 338 

Flow  and  Measurement  of,  in  Open  Channels,  Works  of  Reference  on .  .     89 

Formulas  for  Flow  of 61 

Gathering-Cribs  for    107 

Ground,  Motion  of 91 

Measurement  of  Canal 85 

Measurement  of,  in  Pipes 350 

Meter,  Foote's 87 

Venturi 350 

Methods  of  Applying •• . .   321 

Motion  of 60 

Motors 526 

Physical  Properties  of 58 

Power  of  Falling  524 

Pressure  of 59 

Quantity  per  Service  and  Irrigation  Period    53 

Relation  of,  to  Plant  Growth    313 

Scouring  Effect  of  Falling 183 

Seepage  of  31 

Sources  of  Earth 91 

Other  Subsurface 107 

Storage,  Effect  of  Evaporation  on    28 

Supply  and  Land,  Relation  between 126 

of  Reservoir  Site  to    354 

Tunneling  for 105 

Units  of  Measure  of,  Table ..........     48 

Velocities  of  Flow  of 65,  148 

Weight  of  58 

Water -cushion  on  Wooden  Fall 264 

Water -cushions J86 


INDEX  623 


Water-logging 35 

Prevention  of    35 

Water-power,  Uses  of 536 

Water-pressure  Engines    537 

Water  Users'  Associations 569 

Water-wheel,  Breast 526 

Horizontal  526 

Hurdy-gurdy 526 

Mid-stream    528 

Overshot    526 

Pelton .....  526,  534 

Poncelet 528 

Turbine 532 

Undershot 5?6,  527 

Vertical    526 

Wave  Heights  and  Fetch    380 

Weeds    44 

Wegmann,  Edward,  Jr 407,  412,  418,  508 

Profile  Type  for  Masonry  Dam 410 

Weir  Aprons 183 

Arizona  Canal 180 

Assiout 122,  457 

Bear  River  Canal 180 

Calloway  Canal    168 

Cohoes  Iron  Rollerway  196 

Concrete,  Ashlar  Facing  194 

Conditions  of  using  Rectangular 79 

Corbett 201 

Croton 192 

Formulas,  Francis*    78 

French  Movable .  176 

Gates  and  Shutters,  Automatic    488,  491 

Gauge  Heights 80 

Goulburn  Masonry  and  Iron  Drop-gate 196 

Granite  Reef 202,  215 

Henares,  Spain 194 

Holyoke,  Mass 208 

Laguna    175,  214 

Leasburg  190 

Lower  Yellowstone    182 

Minidoka,  Idaho    385 

Movable  French 176 

Norwich  Water  Power  Co.,  Conn 191 

Pequannock  River,  Newark,  N.  J 206 

Reinforced  Concrete    200 

Rolling  Lift 177 

Rubble  Masonry    195 

Sidhnai 174 


624  INDEX 

FACE 

Weir  Soane  172 

Theresa 200 

Vir,  India    195 

Weirs,  Broad-crested »  80 

of  Brush  and  Bowlders 165 

Classes  of    165 

Construction  of  Crib 179 

Crib  and  Rock 179 

Discharge  over 80,  482 

Diversion 164 

Flashboard  or  Open-frame 168 

Indian  Type 170 

of  Iron 196 

Movable 176 

Masonry   188 

founded  on  Cribs   192 

Piles 190 

and  Cribs 191 

Wells 192 

and  Iron  Drop-gate   196 

Open  Indian  Type 170 

Measuring 77 

Ogee  or  Rollerway  Shaped 185,  196 

Open  and  Closed 166 

Open  Iron  Frame,  French  Type 176 

Pile 1 66 

Rectangular  Measuring 77 

Relation  of,  to  Regulators    227 

Rollerway  or  Ogee-shaped 185,  196 

Table  of  Discharge  over  Rectangular 81 

Trapezoidal 83 

Trapezoidal    79 

Waste,  Discharge  of    ' 482 

Shapes  of  484 

Wooden  Crib  and  Rock 179 

Weisbach,  P.  J 90,  312,  352,  508,  563 

Wells,  Artesian 94 

Capacity  and  Cost  of 95,  507 

Drilling,  Manner    97 

Machines 98 

Process  of    100 

Examples  of    94 

Power-Pumped 103 

Sizes  of 96 

Sources  of   93 

Stove-pipe  Casing  for 101 

Wells  as  Foundation  for  Masonry  Weirs 192 

Supplying  Capacity  of  Common 102 


INDEX  625 


Wheel,  Persian   515 

Whiting,  J.  G 312 

Wide-Crested  Dams 420 

Wilcox,  W 312 

Lute .352 

Williston  Pumping-Plant    554 

Wilson,  H.  M 33,  46,  57,  312,  563 

Windlass,  Wooden  Regulator  Gate  raised  by    234 

Windmills    515 

Capacity  and  Economy  of    516 

Value  of,  as  Irrigating  Machines 523 

Varieties  of    519 

Winch,  Regulator  Gate  Lifted  by  Travelling 235 

Wisner,  George  Y 415 

Wolff,  A.  R .      517,563 

Wooden  Lateral  Heads 304 

Fall  with  Water-cushion    264 

Fall,  Simple,  Vertical 263 

Flashboard  Regulators 232 

Inverted  Siphons 289 

Pipes,  Construction  of   346 

Rapids  or  Chutes 264 

Regulator  Gate  lifted  by  Lever    234 

Windlass 234 

Stave  Pipes    346 

Work,  Equivalent  Units  of 547 

Works,  Canal  Diversion 1 26 

Works  on  Canals,  Maintenance  and  Supervision  of 560 

Works  of  Reference — Alkali,  Drainage,  and  Sedimentation 46 

Application  of  WTater  and  Pipe  Irrigation 352 

Artesian  Wells    117 

Diversion  and  Canal  Works 311 

Duty  of  Water 57 

Evaporation,  Absorption,  and  Seepage    33 

Flow  and  Measurement  of  Water  in  Open  Channels    .  .  89 

Precipitation,  Runoff,  and  Stream  Flow    2  r 

Pumping   562 

Sedimentation 46 

Sewage  Irrigation 117 

Storage  Works 507 

Subsurface-water  Sources 117 

Works,  Storage 352 

Yellowstone  Canal  Wasteway    ,.  .  245 

Weir 182 

Yuma  Project,  Colorado  River    214 

Zola  Dam    4 1 6,  47 1 


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